Prepreg, laminate, and method of production of prepreg

ABSTRACT

A prepreg provided with a first resin layer and a second resin layer which is formed on this first resin layer, wherein the first resin layer is formed by a first resin composition, the second resin layer is a layer which comprises a resin layer which is formed by a second resin composition which is different from the first resin composition and in which a fiber base material is contained, the second resin layer is provided with a fiber base material-containing layer which contains the fiber base material, an A layer which is positioned at an opposite side of the first resin layer side of the fiber base material-containing layer and which does not contain the fiber base material, and a B layer which is positioned at the first resin layer side of the fiber base material-containing layer and which does not contain the fiber base material, and said B layer has a thickness which is smaller than the thickness of the first resin layer, is provided.

This is a divisional application of U.S. patent application Ser. No.14/369,854, filed Jun. 30, 2014, which in turn is a National PhaseApplication of PCT/JP2012/083812, filed Dec. 27, 2012, which claimspriority to Japanese Patent Application Nos. 2011-289400, 2011-289416,2011-289428 and 2011-289439, all filed Dec. 28, 2011. The disclosures ofthe prior applications are hereby incorporated by reference in theirentireties.

TECHNICAL FIELD

The present invention relates to a prepreg, a laminate, and a method ofproduction of a prepreg.

BACKGROUND ART

Along with the smaller size and increased thinness of electroniccomponents, electronic equipment, etc. in recent years, smaller size andincreased thinness of the circuit boards etc. which are used for thesehave been sought. For this reason, along with this, in the circuitboards, it is required to form the higher density circuit wiringpatterns.

To form such high density circuit wiring patterns, multilayer structurecircuit boards have been used, and the layers which form the circuitboards have been made smaller in thicknesses. When increasing thethinness of such a multilayer structure circuit board, from theviewpoint of enabling the mechanical strength of the circuit board to bemaintained even when increasing the thinness, the method of using aprepreg which contains glass fiber or other fiber base material as thematerial which forms the interlayer insulating layer of the multilayerstructure circuit board has been studied.

For example, Patent Document 1 discloses the art of using a resinvarnish which contains an epoxy resin to obtain two types ofthermosetting resin films with different thicknesses and sandwichingglass fibers between the obtained thermosetting resin films to obtain aprepreg. However, in the art of this Patent Document 1, the cured shapedarticle which is obtained by curing the prepreg is large in variation ofsurface roughness. For this reason, when using electroless plating etc.to form a conductor layer, there was the problem that the metal platingfilm was low in formability and the conductor layer could not be formedwell. Further, in the art of this Patent Document 1, if reducing thethickness of the obtained prepreg to deal with the increased thinness ofmultilayer structure circuit boards, there was the inconvenience thatwhen laminating the prepreg on the circuit patterns, the glass fiberswhich are contained in the prepreg are pushed up by the circuitpatterns, the glass fibers end up being exposed at the prepreg surfacedue to this, and therefore the cured shaped article which is obtained bycuring the prepreg ends up varying more greatly in surface roughness.

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: Japanese Patent Publication No. 2007-176169A

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

An object of the present invention is to provide a prepreg which cangive a cured shaped article which is small in variation of surfaceroughness, excellent in surface flatness, and can form a platedconductor layer which is substantially free of uneven plating. Further,the present invention has as its object the provision of a laminatewhich is obtained using such a prepreg.

Means for Solving the Problems

The inventors discovered that by providing a prepreg with a first resinlayer which is comprised of a first resin composition and a second resinlayer which is comprised of a second resin composition, comprising thesecond resin layer by a fiber base material-containing layer whichcontains a fiber base material, an A layer which is positioned at theopposite side to the first resin layer side and which does not contain afiber base material, and a B layer which is positioned at the firstresin layer side and which does not contain a fiber base material, andmaking the thickness of the B layer smaller than the thickness of thefirst resin layer, the above objects can be achieved and therebycompleted the present invention.

That is, according to the present invention, there are provided:

[1] A prepreg provided with a first resin layer and a second resin layerwhich is formed on the first resin layer, wherein the first resin layeris formed by a first resin composition, the second resin layer is alayer which comprises a resin layer which is formed by a second resincomposition which is different from the first resin composition and inwhich a fiber base material is contained, the second resin layer isprovided with a fiber base material-containing layer which contains thefiber base material, an A layer which is positioned at an opposite sideof the first resin layer side of the fiber base material-containinglayer and which does not contain the fiber base material, and a B layerwhich is positioned at the first resin layer side of the fiber basematerial-containing layer and which does not contain the fiber basematerial, and the B layer has a thickness which is smaller than thethickness of the first resin layer,[2] The prepreg as set forth in [1], wherein the B layer has a thicknessof over 0 μm to 5 μm,[3] The prepreg as set forth in [2], wherein the B layer has a thicknessof over 0 μm to 2 μm,[4] The prepreg as set forth in any one of [1] to [3], wherein a ratioof thickness of the A layer to a thickness of the prepreg as a whole is25% or more,[5] The prepreg as set forth in any one of [1] to [4], wherein the firstresin layer has a thickness of 7 μm or less,[6] The prepreg as set forth in [5], wherein the first resin layer has avariation in thickness of ±1 μm in range, the first resin compositionand the second resin composition are in an uncured or semicured state,and the first resin composition has a viscosity which is higher than theviscosity of the second resin composition,[7] The prepreg as set forth in any one of [1] to [6], wherein the firstresin layer is a plateable layer for forming a plated conductor, and thesecond resin layer is an adhesive layer for adhesion with the substrate,[8] The prepreg as set forth in any one of [1] to [7], wherein at leastthe second resin layer contains an inorganic filler, and a ratio ofcontent of inorganic filler in the second resin layer is 50 to 80 wt %in range and is greater than a ratio of content of inorganic filler inthe first resin layer,[9] A laminate obtained by bonding the prepreg as set forth in any oneof [1] to [8] with a surface of said second resin layer side to asubstrate,[10] A method of production of the prepreg as set forth in any one of[1] to [8] comprising a step A of using the first resin composition toform the first resin layer, a step B of superposing the fiber basematerial on the first resin layer, and a step C of impregnating thesecond resin composition in the fiber base material after the step B,where, when impregnating the second resin composition in the fiber basematerial in the step C, the B layer is formed between the fiber basematerial and the first resin layer,[11] The method of production of a prepreg as set forth in [10] furthercomprising, before superposing the fiber base material on the firstresin layer, forming the B layer comprised of the second resincomposition on the first resin layer and superposing the fiber basematerial through the B layer,[12] The method of production of the prepreg as set forth in any one of[1] to [8] comprising a step A of using the first resin composition toform the first resin layer and a step D of superposing the fiber basematerial in which the second resin composition is impregnated on thefirst resin layer to form the second resin layer, and[13] The method of production of the prepreg as set forth in [12]further comprising, after superposing the fiber base material in whichthe second resin composition is impregnated on the first resin layer,further applying or casting the second resin composition on the fiberbase material to form the second resin layer.

Further, according to the present invention, as other techniques toachieve the above objects, there are provided:

[1a] A prepreg provided with a first resin layer which is comprised of afirst resin composition and a second resin layer which is comprised of asecond resin composition which is different from the first resincomposition and contains a fiber base material in the second resinlayer, wherein the second resin composition is interposed between thefirst resin layer and the fiber base material which is contained in thesecond resin layer and a distance between the first resin layer and thefiber base material is over 0 μm to 2 μm,[2a] The prepreg as set forth in [1a], wherein the first resin layer isa plateable layer for forming a plated conductor, and the second resinlayer is an adhesive layer for adhesion with a substrate,[3a] The prepreg as set forth in [1a] or [2a], wherein at least thesecond resin layer contains an inorganic filler, and a ratio of contentof inorganic filler in the second resin layer is 50 to 80 wt % in rangeand is larger than the ratio of content of inorganic filler in the firstresin layer,[4a] A laminate obtained by bonding the prepreg as set forth in any oneof [1a] to [3a] with a surface of said second resin layer side to asubstrate,[5a] A method of production of the prepreg as set forth in any one of[1a] to [3a] comprising a step of using the first resin composition toform the first resin layer and a step of superposing the fiber basematerial on the first resin layer and impregnating the second resincomposition in the fiber base material while forming the second resinlayer,[6a] The method of production of the prepreg as set forth in [5a]further comprising, before superposing the fiber base material on thefirst resin layer, forming a layer comprised of the second resincomposition on the first resin layer and superposing the fiber basematerial through the layer comprised of the second resin composition,[7a] A method of production of the prepreg as set forth in any one of[1a] to [3a] comprising a step of using the first resin composition toform the first resin layer and a step of superposing the fiber basematerial in which the second resin composition is impregnated on thefirst resin layer to form the second resin layer, and[8a] The method of production of the prepreg as set forth in [7a]further comprising, after superposing the fiber base material in whichthe second resin composition is impregnated on the first resin layer,further applying or casting the second resin composition on the fiberbase material to form the second resin layer.

Alternatively, according to the present invention, as still othertechniques to achieve the above objects, there are provided:

[1b] A prepreg provided with a first resin layer which is comprised of afirst resin composition and a second resin layer which is comprised of asecond resin composition which is different from the first resincomposition and contains a fiber base material in the second resinlayer, wherein the second resin composition is interposed between thefirst resin layer and the fiber base material which is contained in thesecond resin layer, a distance between the first resin layer and thefiber base material is over 0 μm to 5 μm, and the distance is smallerthan the thickness of the first resin layer,[2b] The prepreg as set forth in [1b], wherein the first resin layer hasa thickness of 7 μm or less,[3b] The prepreg as set forth in [1b] or [2b], wherein the first resinlayer is a plateable layer for forming a plated conductor, and thesecond resin layer is an adhesive layer for adhesion with a substrate,[4b] The prepreg as set forth in any one of [1b] to [3b], wherein atleast the second resin layer contains an inorganic filler, and a ratioof content of inorganic filler in the second resin layer is 50 to 80 wt% in range and is larger than the ratio of content of inorganic fillerin the first resin layer,[5b] A laminate obtained by bonding the prepreg as set forth in any oneof [1b] to [4b] with a surface of said second resin layer side to asubstrate,[6b] A method of production of the prepreg as set forth in any one of[1b] to [4b] comprising a step of using the first resin composition toform the first resin layer and a step of superposing the fiber basematerial on the first resin layer and impregnating the second resincomposition in the fiber base material while forming the second resinlayer,[7b] The method of production of the prepreg as set forth in [6b]further comprising, before superposing the fiber base material on thefirst resin layer, forming a layer comprised of the second resincomposition on the first resin layer and superposing the fiber basematerial through the layer comprised of the second resin composition,[8b] The method of production of the prepreg as set forth in any one of[1b] to [4b] comprising a step of using the first resin composition toform the first resin layer and a step of superposing the fiber basematerial in which the second resin composition is impregnated on thefirst resin layer to form the second resin layer, and[9b] The method of production of the prepreg as set forth in [8b]further comprising, after superposing the fiber base material in whichthe second resin composition is impregnated on the first resin layer,further applying or casting the second resin composition on the fiberbase material to form the second resin layer.

Further, according to the present invention, as still other techniquesto achieve the above objects, there are provided:

[1c] A prepreg which is produced through a step of forming a first resinlayer which is comprised of a first resin composition and a step ofsuperposing the fiber base material on the first resin layer andimpregnating a second resin composition which is different from thefirst resin composition in the fiber base material while forming thesecond resin layer, wherein the second resin layer is provided with afiber base material-containing layer which contains the fiber basematerial and an A layer which does not contain the fiber base materialat an opposite side of the first resin layer and a ratio of thickness ofthe A layer to thickness of the prepreg as a whole is 25% or more,[2c] a prepreg as set forth in [1c] obtained by, before superposing thefiber base material on the first resin layer, forming a layer comprisedof the second resin composition on the first resin layer and superposingthe fiber base material through the layer comprised of the second resincomposition,[3c] A prepreg which is produced through a step of forming a first resinlayer which is comprised of a first resin composition and a step ofsuperposing the fiber base material in which a second resin compositionwhich is different from the first resin composition is impregnated onthe first resin layer, wherein the second resin layer is provided with afiber base material-containing layer which contains the fiber basematerial and an A layer which does not contain the fiber base materialat an opposite side of the first resin layer and a ratio of thickness ofthe A layer to thickness of the prepreg as a whole is 25% or more,[4c] The prepreg as set forth in [3c] obtained by, after the fiber basematerial in which the second resin composition is impregnated issuperposed on the first resin layer, further applying or casting thesecond resin composition to form the second resin layer,[5c] The prepreg as set forth in any one of [1c] to [4c], wherein thesecond resin composition is interposed between the first resin layer andthe fiber base material which is contained in the second resin layer,[6c] The prepreg as set forth in any one of [1c] to [5c], wherein thefirst resin layer has a thickness of 7 μm or less,[7c] The prepreg as set forth in any one of [1c] to [6c], wherein thefirst resin layer is a plateable layer for forming a plated conductor,and the second resin layer is an adhesive layer for adhesion with asubstrate,[8c] The prepreg as set forth in any one of [1c] to [7c], wherein atleast the second resin layer contains an inorganic filler, and a ratioof content of inorganic filler in the second resin layer is 50 to 80 wt% in range and is larger than the ratio of content of inorganic fillerin the first resin layer,[9c] A laminate obtained by bonding the prepreg as set forth in any oneof [1c] to [8c] with a surface of said second resin layer side to asubstrate,[10c] A method of production of a prepreg comprising a step of forming afirst resin layer which is comprised of a first resin composition and astep of superposing the fiber base material on the first resin layer andimpregnating a second resin composition which is different from thefirst resin composition in the fiber base material while forming thesecond resin layer, and[11c] A method of production of a prepreg comprising a step of forming afirst resin layer which contains a first resin composition and a step ofsuperposing the fiber base material in which a second resin compositionwhich is different from the first resin composition is impregnated onthe first resin layer to form the second resin layer.

Alternatively, according to the present invention, as still othertechniques to achieve the above objects, there are provided:

[1d] A prepreg provided with a first resin layer which is comprised of afirst resin composition and a second resin layer which is comprised of asecond resin composition which is different from the first resincomposition and contains a fiber base material in the second resinlayer, wherein the first resin layer has a thickness of 7 μm or less andhas a variation of thickness of ±1 μm in range, the first resincomposition which forms the first resin layer and the second resincomposition which forms the second resin layer are in an uncured orsemicured state, and the first resin composition which forms the firstresin layer has a viscosity which is higher than the viscosity of thesecond resin composition which forms the second resin layer,[2d] The prepreg as set forth in [1d], wherein the layer which iscomprised of the second resin composition is interposed between thefirst resin layer and the fiber base material which is contained in thesecond resin layer,[3d] The prepreg as set forth in [1d] or [2d], wherein the first resinlayer is a plateable layer for forming a plated conductor, and thesecond resin layer is an adhesive layer for adhesion with a substrate,[4d] The prepreg as set forth in any one of [1d] to [3d], wherein atleast the second resin layer contains an inorganic filler, and a ratioof content of inorganic filler in the second resin layer is 50 to 80 wt% in range and is larger than the ratio of content of inorganic fillerin the first resin layer,[5d] A laminate obtained by bonding the prepreg as set forth in any oneof [1d] to [4d] with a surface of said second resin layer side to asubstrate,[6d] A method of production of the prepreg as set forth in any one of[1d] to [4d] comprising a step of using the first resin composition toform the first resin layer and a step of superposing the fiber basematerial on the first resin layer and impregnating the second resincomposition in the fiber base material while forming the second resinlayer,[7d] The method of production of the prepreg as set forth in [6d]further comprising, before superposing the fiber base material on thefirst resin layer, forming the layer comprised of the second resincomposition on the first resin layer and superposing the fiber basematerial through the layer comprised of the second resin composition,[8d] A method of production of the prepreg as set forth in any one of[1d] to [4d] comprising a step of using the first resin composition toform the first resin layer and a step of superposing the fiber basematerial in which the second resin composition is impregnated on thefirst resin layer on the fiber base material to form the second resinlayer, and[9d] The method of production of the prepreg as set forth in [8d]further comprising, after superposing the fiber base material in whichthe second resin composition is impregnated on the first resin layer,further applying or casting the second resin composition on the fiberbase material to form the second resin layer.

Effects of the Invention

According to the present invention, it is possible to provide a prepregwhich can give a cured shaped article which is small in variation insurface roughness, excellent in surface flatness, and can form a platedconductor layer which is substantially free of uneven plating.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view which shows an example of a prepreg accordingto the present invention.

DESCRIPTION OF EMBODIMENTS

The prepreg of the present invention is provided with a first resinlayer and a second resin layer which is formed on this first resinlayer. The first resin layer is formed by a first resin composition,while the second resin layer is a resin layer which formed by a secondresin composition which is different from the first resin compositionand contains a fiber base material. The second resin layer is providedwith a fiber base material-containing layer which contains the fiberbase material, an A layer which is positioned at an opposite side of thefirst resin layer side of the fiber base material-containing layer andwhich does not contain the fiber base material, and a B layer which ispositioned at the first resin layer side of the fiber basematerial-containing layer and which does not contain the fiber basematerial, where the thickness of the B layer is smaller than thethickness of the first resin layer.

(First Resin Composition)

First, the first resin composition for forming the first resin layerwill be explained. The first resin which is contained in the first resincomposition used in the present invention is not particularly limited,but, for example, an alicyclic olefin polymer, epoxy resin, phenolresin, polyimide resin, triazine resin, melamine resin or modifiedresins which are obtained by modifying these etc. may be mentioned.These may be used alone or as two types or more combined. From theviewpoint of making the prepreg of the present invention cross-linkable,a resin which has cross-linkable functional groups or cross-linkablecarbon-carbon unsaturated bonds is preferable. Among these as well, fromthe viewpoint of achieving a good balance of heat resistance,waterproofness, and electrical characteristics when applying theobtained prepreg to a circuit board, an alicyclic olefin polymer whichcontains polar groups is preferable. Below, a polar group-containingalicyclic olefin polymer as the first resin to be included in the firstresin composition is defined as a “polar group-containing alicyclicolefin polymer (A1)” and the case using a polar group-containingalicyclic olefin polymer (A1) as a first resin will be explained as anexample. Note that, the following explanation can be similarly suitablyapplied even when using a resin other than a polar group-containingalicyclic olefin polymer (A1).

As the alicyclic structure which forms the polar group-containingalicyclic olefin polymer (A1) used in the present invention, acycloalkane structure, cycloalkene structure, etc. may be mentioned, butfrom the viewpoint of the mechanical strength, heat resistance, etc., acycloalkane structure is preferable. Further, as the alicyclicstructure, a monocyclic, polycyclic, condensed polycyclic, or bridgedring structure, polycyclic structure comprised of a combination of theseetc. may be mentioned. The number of carbon atoms which form thealicyclic structure is not particularly limited, but is usually 4 to 30,preferably 5 to 20, more preferably 5 to 15 in range. When the number ofcarbon atoms which form the alicyclic structure is in this range, thevarious characteristics of the mechanical strength, heat resistance, andformability are balanced to a high degree, so this is preferable. Notethat, the polar group-containing alicyclic olefin polymer (A1) itselfusually exhibits thermoplasticity, but if used in combination with acuring agent, thermosettability can be exhibited.

The alicyclic structure of the polar group-containing alicyclic olefinpolymer (A1) is comprised of olefin monomer units which have analicyclic structure formed by carbon atoms (that is, alicyclic olefinmonomer units) or monomer units which can be viewed the same asalicyclic olefin monomer units (below, these being referred to togetheras “alicyclic olefin monomer units”). The polar group-containingalicyclic olefin polymer (A1) may contain not only alicyclic olefinmonomer units, but also other monomer units. The ratio of the alicyclicolefin monomer units in the polar group-containing alicyclic olefinpolymer (A1) is not particularly limited, but is usually 30 to 100 wt %,preferably 50 to 100 wt %, more preferably 70 to 100 wt %. If the ratioof the alicyclic olefin monomer units is too small, the heat resistanceis inferior, so this is not preferable. The monomer units other thanalicyclic olefin monomer units are not particularly limited and may besuitably selected in accordance with the objective.

The polar group of the polar group-containing alicyclic olefin polymer(A1) is not particularly limited, but an alcoholic hydroxyl group,phenolic hydroxyl group, carboxyl group, alkoxyl group, epoxy group,glycidyl group, oxycarbonyl group, carbonyl group, amino group, estergroup, carboxylic acid anhydride group, sulfonic acid group, phosphoricacid group, etc. may be mentioned, but among these as well, a carboxylgroup, carboxylic acid anhydride group, and phenolic hydroxyl group arepreferable, while a carboxylic acid anhydride group is more preferable.Note that, the polar group-containing alicyclic olefin polymer (A1) maybe one which has two or more types of polar groups. Further, the polargroups of the polar group-containing alicyclic olefin polymer (A1) maybe directly bonded to the atoms forming the mainchain of the polymer ormay be bonded through methylene groups, oxy groups,oxycarbonyloxyalkylene groups, phenylene groups, or other bivalentgroups. The polar groups may be bonded to alicyclic olefin monomer unitsor may be bonded to monomer units other than alicyclic olefin monomerunits. The content of the monomer units which has polar groups in thepolar group-containing alicyclic olefin polymer (A1) is not particularlylimited, but is usually 4 to 60 mol % in 100 mol % of the total monomerunits which form the polar group-containing alicyclic olefin polymer(A1), preferably 8 to 50 mol %.

The polar group-containing alicyclic olefin polymer (A1) used in thepresent invention can, for example, be obtained by the followingmethods. That is, it can be obtained by (1) the method of polymerizingan alicyclic olefin which has polar groups with, according to need, theaddition of other monomers, (2) the method of copolymerizing analicyclic olefin which does not have polar groups together with amonomer which has polar groups, (3) the method of polymerizing anaromatic olefin which has polar groups with, according to need, theaddition of other monomers and hydrogenating the aromatic ring part ofthe obtained polymer, (4) the method of copolymerizing an aromaticolefin which does not have polar groups with a monomer which has polargroups and hydrogenating the aromatic ring part of the obtained polymer,or (5) the method of introducing into the alicyclic olefin polymer whichdoes not have polar groups a compound which has polar groups by amodification reaction, or (6) the method of converting the polar groupsof the alicyclic olefin polymer which has polar groups (for examplecarboxylic acid ester groups etc.) which are obtained by the above (1)to (5) by, for example, hydrolysis etc. to other polar groups (forexample, carboxyl groups), etc. Among these as well, a polymer which isobtained by the method of the above-mentioned (1) is suitable.

For the polymerization method for obtaining the polar group-containingalicyclic olefin polymer (A1) used in the present invention, ringopening polymerization or addition polymerization may be used, but inthe case of ring opening polymerization, it is preferable to hydrogenatethe obtained ring-opening polymer.

As specific examples of the alicyclic olefin which has polar groups,5-hydroxycarbonylbicyclo[2.2.1]hept-2-ene,5-methyl-5-hydroxycarbonylbicyclo[2.2.1]hept-2-ene,5-carboxymethyl-5-hydroxycarbonylbicyclo[2.2.1]hept-2-ene,9-hydroxycarbonyltetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,9-methyl-9-hydroxycarbonyltetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,9-carboxymethyl-9-hydroxycarbonyltetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,5-exo-6-endo-dihydroxycarbonylbicyclo[2.2.1]hept-2-ene,9-exo-10-endo-dihydroxycarbonyltetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,and other alicyclic olefins which have carboxyl groups;bicyclo[2.2.1]hept-2-ene-5,6-dicarboxylic acid anhydride,tetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene-9,10-dicarboxylic acidanhydride,hexacyclo[10.2.1.1^(3,10).1^(5,8).0^(2,11).0^(4,9)]heptadeca-6-ene-13,14-dicarboxylicacid anhydride, and other alicyclic olefins which have carboxylic acidanhydride groups;9-methyl-9-methoxycarbonyltetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,5-methoxycarbonyl-bicyclo[2.2.1]hept-2-ene,5-methyl-5-methoxycarbonyl-bicyclo[2.2.1]hept-2-ene, and other alicyclicolefins which have carboxylic acid ester groups;(5-(4-hydroxyphenyl)bicyclo[2.2.1]hept-2-ene,9-(4-hydroxyphenyl)tetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,N-(4-hydroxyphenyl) bicyclo[2.2.1]hept-5-ene-2,3-dicarboxyimide, andother alicyclic olefins which have phenolic hydroxyl groups, etc. may bementioned. These may be used alone or may be used in two or more types.

As specific examples of the alicyclic olefin which does not have polargroups, bicyclo[2.2.1]hept-2-ene (common name: norbornene),5-ethyl-bicyclo[2.2.1]hept-2-ene, 5-butyl-bicyclo[2.2.1]hept-2-ene,5-ethylidene-bicyclo[2.2.1]hept-2-ene,5-methylidene-bicyclo[2.2.1]hept-2-ene,5-vinyl-bicyclo[2.2.1]hept-2-ene, tricyclo[5.2.1.0^(2,6)]deca-3,8-diene(common name: dicyclopentadiene),tetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene (common name:tetracyclododecene),9-methyl-tetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,9-ethyl-tetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,9-methylidene-tetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,9-ethylidene-tetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,9-methoxycarbonyltetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,9-vinyl-tetracyclo [6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,9-propenyl-tetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,9-phenyl-tetracyclo[6.2.1.1^(3,6).0^(2,7)]dodec-4-ene,tetracyclo[9.2.1.0^(2,10).0^(3,8)]tetradeca-3,5,7,12-tetraene,cyclopentene, cyclopentadiene, etc. may be mentioned. These may be usedalone or may be used in two or more types.

As examples of the aromatic olefin which does not have polar groups,styrene, α-methylstyrene, divinylbenzene, etc. may be mentioned. Whenthese specific examples have the polar groups, the example of anaromatic olefin which has polar groups may be mentioned. These may beused alone or may be used in two or more types.

As the monomer which can be copolymerized with alicyclic olefins oraromatic olefins and which has polar groups other than alicyclic olefinswhich have polar groups, ethylenically unsaturated compounds which havepolar groups may be mentioned. As specific examples of these, acrylicacid, methacrylic acid, α-ethylacrylic acid, 2-hydroxyethyl(meth)acrylicacid, maleic acid, fumaric acid, itaconic acid, and other unsaturatedcarboxylic acid compounds; maleic anhydride, butenylsuccinic anhydride,tetrahydrophthalic anhydride, citraconic anhydride, and otherunsaturated carboxylic acid anhydrides; etc. may be mentioned. These maybe used alone or may be used in two or more types.

As the monomer which can be copolymerized with alicyclic olefins oraromatic olefins and which does not have polar groups other thanalicyclic olefins, unsaturated compounds which do not have polar groupsmay be mentioned. As specific examples of these, ethylene, propylene,1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene,3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene,4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene,3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene,1-hexadecene, 1-octadecene, 1-eicosene, and other C₂ to C₂₀ ethylene orα-olefins; 1,4-hexadiene, 4-methyl-1,4-hexadiene,5-methyl-1,4-hexadiene, 1,7-octadiene, and other unconjugated dienes;etc. may be mentioned. These may be used alone or may be used in two ormore types.

The polar group-containing alicyclic olefin polymer (A.1) used in thepresent invention is not particularly limited in molecular weight, but aweight average molecular weight converted to polystyrene, measured bygel permeation chromatography using tetrahydrofuran as a solvent, of1,000 to 1,000,000 in range is preferable, 3,000 to 500,000 in range ismore preferable, and 5,000 to 300,000 in range is particularlypreferable. By making the weight average molecular weight in this range,it is possible to make the obtained prepreg excellent in mechanicalstrength and workability.

As the polymerization catalyst in the case of obtaining the polargroup-containing alicyclic olefin polymer (A.1) used in the presentinvention by ring opening polymerization, a conventionally knownmetathesis polymerization catalyst can be used. As the metathesispolymerization catalyst, a transition metal compound which containsatoms of Mo, W, Nb, Ta, Ru, etc. may be illustrated. Among these,compounds which contain Mo, W, or Ru are high in polymerization activityand therefore preferred. As specific examples of particularly preferablemetathesis polymerization catalysts, (1) catalysts which include, asmain catalysts, molybdenum or tungsten compounds which has halogengroups, imide groups, alkoxyl groups, allyloxy groups, or carbonylgroups as ligands and include organometallic compounds as secondingredients and (2) metal carbene complex catalysts which have Ru as thecentral metal may be mentioned.

As examples of compounds which are used as the main catalysts in thecatalysts of the above (1), MoCl₅, MoBr₅, and other halogenatedmolybdenum compounds and WCl₆, WOCl₄, tungsten(phenylimide)tetrachloridediethyl ether and other halogenated tungsten compounds may be mentioned.Further, as the organometallic compounds which are used as the secondingredients in the catalyst of the above (1), organometallic compoundsof Group I, Group II, Group XII, Group XIII, or Group XIV of thePeriodic Table may be mentioned. Among these, organolithium compounds,organomagnesium compounds, organozinc compounds, organoaluminumcompounds, and organotin compounds are preferable, while organolithiumcompounds, organoaluminum compounds, and organotin compounds areparticularly preferable. As organolithium compounds, n-butyllithium,methyllithium, phenyllithium, neopentyllithium, neophyllithium, etc. maybe mentioned. As organomagnesium compounds, butylethylmagnesium,butyloctylmagnesium, dihexylmagnesium, ethylmagnesium chloride,n-butylmagnesium chloride, allylmagnesium bromide, neopentylmagnesiumchloride, neophylmagnesium chloride, etc. may be mentioned. Asorganozinc compounds, dimethylzinc, diethylzinc, diphenylzinc, etc. maybe mentioned. As organoaluminum compounds, trimethylaluminum,triethylaluminum, triisobutylaluminum, diethylaluminum chloride,ethylaluminum sesquichloride, ethylaluminum dichloride, diethylaluminumethoxide, ethylaluminum diethoxide, etc. may be mentioned. Furthermore,it is possible to use aluminoxane compounds which are obtained byreaction of these organoaluminum compounds and water. As organotincompounds, tetramethyltin, tetra(n-butyl)tin, tetraphenyltin, etc. maybe mentioned. The amounts of these organometallic compounds differdepending on the organometallic compounds used, but by molar ratio withrespect to the central metal of the main catalyst, 0.1 to 10,000 timesis preferable, 0.2 to 5,000 times is more preferable, and 0.5 to 2,000times is particularly preferable.

Further, as the metal carbene complex catalyst having Ru as a centralmetal in the above (2), (1,3-dimesitylimidazolidin-2-ylidene)(tricyclohexylphosphine)benzylideneruthenium dichloride,bis(tricyclohexylphosphine)benzylideneruthenium dichloride,tricyclohexylphosphine-[1,3-bis(2,4,6-trimethylphenyl)-4,5-dibromoimidazol-2-ylidene]-[benzylidene]rutheniumdichloride, 4-acetoxybenzylidene(dichloro)(4,5-dibromo-1,3-dimesityl-4-imidazolin-2-ylidene)(tricyclohexylphosphine)ruthenium, etc. may be mentioned.

The ratio of use of the metathesis polymerization catalyst is, by molarratio with respect to the monomers which are used for the polymerization(transition metal in metathesis polymerization catalyst:monomers),usually 1:100 to 1:2,000,000 in range, preferably 1:200 to 1:1,000,000in range. If the amount of the catalyst is too great, the removal of thecatalyst becomes difficult, while if too small, a sufficientpolymerization activity is liable to be unable to be obtained.

The polymerization reaction is usually performed in an organic solvent.The organic solvent which is used is not particularly limited so long asthe polymer dissolves or disperses under predetermined conditions andthe solvent does not affect the polymerization, but one which isgenerally used industrially is preferable. As specific examples of theorganic solvent, pentane, hexane, heptane, and other aliphatichydrocarbons; cyclopentane, cyclohexane, methylcyclohexane,dimethylcyclohexane, trimethylcyclohexane, ethylcyclohexane,diethylcyclohexane, decahydronaphthalene, bicycloheptane,tricyclodecane, hexahydroindene, cyclooctane, and other aliphatichydrocarbons; benzene, toluene, xylene, and other aromatic hydrocarbons;dichloromethane, chloroform, 1,2-dichloroethane, and otherhalogen-containing aliphatic hydrocarbons; chlorobenzene,dichlorobenzene, and other halogen-containing aromatic hydrocarbons;nitromethane, nitrobenzene, acetonitrile, and other nitrogen-containinghydrocarbons; diethyl ether, tetrahydrofuran, and other ethers; anisole,phenetol, and other aromatic ethers; etc. may be mentioned. Among theseas well, the industrially generally used aromatic hydrocarbons andaliphatic hydrocarbons, alicyclic hydrocarbons, ethers, and aromaticethers are preferable.

The use amount of the organic solvent is preferably an amount whichgives a concentration of the monomers in the polymerization solution of1 to 50 wt %, more preferably 2 to 45 wt %, particularly preferably 3 to40 wt %. If the concentration of the monomers is less than 1 wt %, theproductivity becomes poor, while if over 50 wt %, the solution afterpolymerization becomes too high in viscosity and the subsequenthydrogenation reaction sometimes becomes difficult.

The polymerization reaction is started by mixing the monomers which areused for the polymerization and the metathesis polymerization catalyst.As the method for mixing these, the metathesis polymerization catalystsolution may be added to the monomer solution or vice versa. When themetathesis polymerization catalyst which is used is a mixed catalyst ofa main catalyst constituted by a transition metal compound and a secondingredient constituted by an organometallic compound, the reactionsolution of the mixed catalyst may be added to the monomer solution orvice versa. Further, a solution of the transition metal compound may beadded to a mixed solution of the monomers and organometallic compound orvice versa. Furthermore, an organometallic compound may be added to amixed solution of the monomers and a transition metal compound or viceversa.

The polymerization temperature is not particularly limited, but isusually −30° C. to 200° C., preferably 0° C. to 180° C. Thepolymerization time is not particularly limited, but is usually 1 minuteto 100 hours.

As the method of adjusting the molecular weight of the obtained polargroup-containing alicyclic olefin polymer (A1), the method of adding asuitable amount of a vinyl compound or diene compound may be mentioned.The vinyl compound which is used for adjustment of the molecular weightis not particularly limited so long as an organic compound which hasvinyl groups, but 1-butene, 1-pentene, 1-hexene, 1-octene, and otherα-olefins; styrene, vinyltoluene, and other styrenes; ethylvinyl ether,i-butylvinyl ether, allylglycidyl ether, and other ethers; allylchlorideand other halogen-containing vinyl compounds; allyl acetate, allylalcohol, glycidyl methacrylate, and other oxygen-containing vinylcompounds, acrylamide and other nitrogen-containing vinyl compounds,etc. may be mentioned. As the diene compounds which are used foradjustment of the molecular weight, 1,4-pentadiene, 1,4-hexadiene,1,5-hexadiene, 1,6-heptadiene, 2-methyl-1,4-pentadiene,2,5-dimethyl-1,5-hexadiene, and other unconjugated dienes or1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene,1,3-pentadiene, 1,3-hexadiene, and other conjugated dienes may bementioned. The amount of addition of the vinyl compound or dienecompound may be freely selected, in accordance with the molecular weightwhich is targeted, from 0.1 to 10 mol %.

As the polymerization catalyst when obtaining the polar group-containingalicyclic olefin polymer (A1) used in the present invention by additionpolymerization, for example, a catalyst which is comprised of atitanium, zirconium, or vanadium compound and an organoaluminum compoundmay be suitably used. These polymerization catalysts can be used aloneor as two or more types combined. The amount of the polymerizationcatalyst is, by molar ratio of the metal compound in the polymerizationcatalyst:monomers which are used for the polymerization, usually 1:100to 1:2,000,000 in range.

When using a hydrogenated product of a ring-opening polymer as the polargroup-containing alicyclic olefin polymer (A1) used in the presentinvention, the hydrogenation of the ring-opening polymer is usuallyperformed by using a hydrogenation catalyst. The hydrogenation catalystis not particularly limited, but one which is generally used at the timeof hydrogenation of an olefin compound may be suitably employed. Asspecific examples of a hydrogenation catalyst, for example, a Zieglercatalyst which is comprised of a combination of a transition metalcompound and an alkali metal compound such as cobalt acetate andtriethylaluminum, nickel acetyl acetonate and triisobutylaluminum,titanocene dichloride and n-butyllithium, zirconocene dichloride andsec-butyllithium, and tetrabutoxytitanate and dimethylmagnesium;dichlorotris(triphenylphosphine)rhodium, the ones which are described inJapanese Patent Publication No. 7-2929A, Japanese Patent Publication No.7-149823A, Japanese Patent Publication No. 11-209460A, Japanese PatentPublication No. 11-158256A, Japanese Patent Publication No. 11-193323A,Japanese Patent Publication No. 11-209460A, etc., precious metal complexcatalysts comprised of bis(tricyclohexylphosphine) benzylidyneruthenium(IV)dichloride and other ruthenium compounds; and other homogeneouscatalysts may be mentioned. Further, heterogeneous catalysts of nickel,palladium, platinum, rhodium, ruthenium, and other metals carried on acarbon, silica, diatomaceous earth, alumina, titanium oxide, and othercarrier, for example, nickel/silica, nickel/diatomaceous earth,nickel/alumina, palladium/carbon, palladium/silica,palladium/diatomaceous earth, palladium/alumina, etc., may also be used.Further, the above-mentioned metathesis polymerization catalysts mayalso be used as they are as hydrogenation catalysts.

The hydrogenation reaction is usually performed in an organic solvent.The organic solvent may be suitably selected in accordance with thesolubility of the hydrogenated product which is produced. An organicsolvent similar to the organic solvent which is used in theabove-mentioned polymerization reaction may be used. Therefore, afterthe polymerization reaction, there is no need to replace the organicsolvent. It is possible to add a hydrogenation catalyst for a reactionas is. Furthermore, among the organic solvents which are used for theabove-mentioned polymerization reaction, from the viewpoint of their notreacting at the time of the hydrogenation reaction, an aromatichydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons, ethers, oraromatic ethers is preferable, while an aromatic ether is morepreferable.

The hydrogenation reaction conditions may be suitably selected inaccordance with the type of the hydrogenation catalyst which is used.The reaction temperature is usually −20 to 250° C., preferably −10 to220° C., more preferably 0 to 200° C. If lower than −20° C., thereaction velocity becomes slow, while conversely if higher than 250° C.,secondary reactions easily occur. The pressure of the hydrogen isusually 0.01 to 10.0 MPa, preferably 0.05 to 8.0 MPa. If the hydrogenpressure is lower than 0.01 MPa, the hydrogenation reaction velocitybecomes slow, while if higher than 10.0 MPa, a high pressure resistantreaction apparatus becomes necessary.

The time of the hydrogenation reaction is suitably selected forcontrolling the hydrogenation rate. The reaction time is usually 0.1 to50 hours in range. It is possible to hydrogenate 50 mol % or more of the100 mol % of carbon-carbon double bonds of the mainchain in the polymer,preferably 70 mol % or more, more preferably 80 mol % or more,particularly preferably 90 mol % or more.

After performing the hydrogenation reaction, it is possible to performprocessing to remove the catalyst which is used for the hydrogenationreaction. The method of removal of the catalyst is not particularlylimited. Centrifugation, filtration, or other methods may be mentioned.Furthermore, it is possible to add water, alcohol, or another catalystdeactivator or add active clay, alumina, diatomaceous earth, or anotheradsorbent so as to promote removal of the catalyst. The polargroup-containing alicyclic olefin polymer (A1) used in the presentinvention may be used as the polymer solution after polymerization orthe hydrogenation reaction or may be used after removal of the solvent,but since dissolution or dispersion of the additives becomes better whenpreparing the resin composition and since the process can be simplified,use as a polymer solution is preferable.

The amount of the polar group-containing alicyclic olefin polymer (A1)as the first resin in the first resin composition used in the presentinvention is preferably made a range whereby the ratio of content of thepolar group-containing alicyclic olefin polymer (A1) as the first resinwith respect to the solid content when made the first resin layer isusually 20 to 90 wt %, preferably 25 to 80 wt %, more preferably 40 to75 wt %. In the present invention, by making the ratio of content of thepolar group-containing alicyclic olefin polymer (A1) as the first resinin the first resin layer in the above range, it is possible to form afirst resin layer which does not become fluid when heating andlaminating the obtained prepreg on a substrate and which does not easilychange in thickness and possible to keep low the surface roughness ofthe first resin layer side of the cured shaped article which is obtainedby curing the obtained prepreg while improving the peel strength withthe plated conductor when forming a plated conductor layer on thesurface.

Further, the first resin composition used in the present inventionpreferably contains, in addition to the polar group-containing alicyclicolefin polymer (A1) as the first resin, the curing agent (A2) from theviewpoint of promoting curing of the first resin layer and improving themechanical strength and heat resistance of the cured product of thelayer. The curing agent (A2) is not particularly limited. It is possibleto use a curing agent which is blended into a resin composition forforming a general electrical insulating film. As the curing agent (A2),it is preferable to use a compound which has two or more functionalgroups which can react with the polar groups which are provided in thepolar group-containing alicyclic olefin polymer (A1) as the first resinforming the first resin composition so as to form bonds.

For example, as the curing agent which is suitably used when using onewhich has carboxyl groups, carboxylic acid anhydride groups or phenolichydroxyl groups as the polar group-containing alicyclic olefin polymer(A1), a polyepoxy compound, polyisocyanate compound, polyamine compound,polyhydrazide compound, aziridine compound, basic metal oxide, organicmetal halogenate, etc. may be mentioned. These may be used alone or maybe used in two or more types.

As the polyepoxy compounds, for example, phenol novolac type epoxycompounds, cresol novolac type epoxy compounds, cresol type epoxycompounds, bisphenol A type epoxy compounds, bisphenol F type epoxycompounds, hydrogenated bisphenol A type epoxy compounds, and otherglycidyl ether type epoxy compounds; alicyclic epoxy compounds, glycidylester type epoxy compounds, glycidyl amine type epoxy compounds,fluorene-type epoxy compounds, polyfunctional epoxy compounds,isocyanulate type epoxy compounds, phosphorus-containing epoxycompounds, and other polyepoxy compounds; and other compounds which havetwo or more epoxy groups in their molecules may be mentioned. These maybe used alone or may be used in two or more types. Among these, from theviewpoint of enabling the prepreg of the present invention to be madeexcellent in mechanical properties, bisphenol A type epoxy compounds,polyphenol type epoxy compounds, or epoxy resins which have alicyclicolefin structures or fluorene structures are preferable. Furthermore,from the viewpoint of making the cured shaped article which is obtainedby curing the resin composition in heat resistance or waterproofness,epoxy resins which have an alicyclic olefin structure are particularlypreferable. Note that, these may be used alone or may be used in two ormore types.

As the bisphenol A type epoxy compounds, for example, product names“jER827, jER828, jER828EL, jER828XA, and jER834” (above all made byMitsubishi Chemical Corporation), product names “EPICLON 840, EPICLON840-S, EPICLON 850, EPICLON 850-S, and EPICLON 850-LC” (above all madeby DIC Corporation, “EPICLON” is a registered trademark), etc. may bementioned. As the polyphenol type epoxy compound, for example, productnames “1032H60 and XY-4000” (above all made by Mitsubishi ChemicalCorporation), etc. may be mentioned. As epoxy resins which havealicyclic olefin structures or fluorene structures, epoxy resins whichhave dicyclopentadiene frameworks (for example, product names “EPICLONHP7200L, EPICLON HP7200, EPICLON HP7200H, EPICLON HP7200HH, and EPICLONHP7200HHH” (above all made by DIC Corporation); product name “Tactix558” (made by Huntsman Advanced Materials); product names “XD-1000-1Land XD-1000-2L” (above all made by Nippon Kayaku Co., Ltd.)), epoxyresins which have fluorene frameworks (for example, product names“Oncoat EX-1010, Oncoat EX-1011, Oncoat EX-1012, Oncoat EX-1020, OncoatEX-1030, Oncoat EX-1040, Oncoat EX-1050, and Oncoat EX-1051” (above allmade by NAGASE & CO., LTD. “Oncoat” is a registered trademark); productnames “OGSOL PG-100, OGSOL EG-200, and OGSOL EG-250)” (above all made byOsaka Gas Chemicals, Co., Ltd. “OGSOL” is a registered trademark)), etc.may be mentioned.

As the polyisocyanate compounds, C₆ to C₂₄ diisocyanates andtriisocyanates are preferable. As examples of diisocyanates,2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate,4,4′-diphenylmethane diisocyanate, hexamethylene diisocyanate,p-phenylene diisocyanate, etc. may be mentioned. As examples of thetriisocyanates, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecanetriisocyanate, bicycloheptane triisocyanate, etc. may be mentioned.These may be used alone or may be used in two or more types.

As the polyamine compounds, C₄ to C₃₀ aliphatic polyamine compoundswhich have two or more amino groups, aromatic polyamine compounds, etc.may be mentioned. Ones, like guanidine compounds, which haveunconjugated nitrogen-carbon double bonds are not included. As thealiphatic polyamine compounds, hexamethylene diamine,N,N′-dicinnamylidene-1,6-hexane diamine, etc. may be mentioned. As thearomatic polyamine compounds, 4,4′-methylenedianiline,m-phenylenediamine, 4,4′-diaminodiphenylether,4′-(m-phenylenediisopropylidene)dianiline,4,4′-(p-phenylenediisopropylidene)dianiline,2,2′-bis[4-(4-aminophenoxy)phenyl]propane, 1,3,5-benzenetriamine, etc.may be mentioned. These may be used alone or may be used in two or moretypes.

As examples of polyhydrazide compounds, isophthalic acid dihydrazide,terephthalic acid dihydrazide, 2,6-naphthalenedicarboxylic aciddihydrazide, maleic acid dihydrazide, itaconic acid dihydrazide,trimellitic acid dihydrazide, 1,3,5-benzenetricarboxylic aciddihydrazide, pyromellitic acid dihydrazide, etc. may be mentioned. Thesemay be used alone or may be used in two or more types.

As aziridine compounds, tris-2,4,6-(1-aziridinyl)-1,3,5-triazine,tris[1-(2-methyl)aziridinyl]phosphinoxide,hexa[1-(2-methyl)aziridinyl]triphosphatriazine, etc. may be mentioned.These may be used alone or may be used in two or more types.

Among the above-mentioned curing agents, from the viewpoint of thereactivity with the polar groups of the polar group-containing alicyclicolefin polymer (A1) being mild and the ease of handling of the resincomposition, polyepoxy compounds are preferable, while glycidyl ethertype epoxy compounds and alicyclic polyepoxy compounds are particularlypreferably used.

In the first resin composition used in the present invention, the amountof the curing agent (A2) is preferably made a range whereby a ratio ofcontent of the curing agent (A2) to the solid content as a whole whenmaking the first resin layer becomes 5 to 50 wt %, more preferably 10 to40 wt %, furthermore preferably 15 to 30 wt %. By making the ratio ofcontent of the curing agent (A2) in the first resin layer in this range,the cured shaped article of the prepreg can be made excellent inmechanical strength and electrical characteristics, so this ispreferred.

Further, the first resin composition used in the present inventionpreferably further contains, in addition to the polar group-containingalicyclic olefin polymer (A1) as the first resin and the curing agent(A2), an inorganic filler (A3). By further including an inorganic filler(A3), it is possible to form a first resin layer which does not becomefluid when heating and laminating the obtained prepreg on a substrateand which does not easily change in thickness and possible to keep lowthe surface roughness of the first resin layer side of the cured shapedarticle which is obtained by curing the obtained prepreg while makingthe peel strength larger.

The inorganic filler (A3) used in the present invention is notparticularly limited, but, for example, calcium carbonate, magnesiumcarbonate, barium carbonate, zinc oxide, titanium oxide, magnesiumoxide, magnesium silicate, calcium silicate, zirconium silicate,hydrated alumina, magnesium hydroxide, aluminum hydroxide, bariumsulfate, silica, talc, clay, etc. may be mentioned. Among these as well,ones which do not degrade or dissolve due to acidic compounds such asthe aqueous solution of permanganate which is used for the surfaceroughening treatment of the cured shaped article which is obtained bycuring the prepreg of the present invention are preferable. Inparticular, silica is preferable. This is because if the aqueoussolution of permanganate or other acidic compound causes the inorganicfiller to degrade or dissolve, the etching will result in deep holesbeing formed.

Further, in the present invention, the inorganic filler (A3) which iscontained in the first resin composition may be one which is treated onits surface in advance by a coupling agent etc. or one which is nottreated on its surface. Note that, the surface treatment can beperformed in the same way as the later explained inorganic filler (B3).

Furthermore, the inorganic filler (A3) is preferably a nonconductive onewhich does not cause the obtained prepreg to drop in dielectriccharacteristics. Further, the inorganic filler (A3) is not particularlylimited in shape. It may be spherical, fibrous, plate-shaped, etc., butto improve the dispersability and stably keep the cured product obtainedby using the resin composition small in surface roughness, a finespherical shape is preferable.

The inorganic filler (A3) has an average particle diameter of preferably0.01 to 0.5 μm, more preferably 0.1 to 0.5 μm, particularly preferably0.15 to 0.4 μm. By making the average particle diameter of the inorganicfiller (A3) in this range, the surface roughness of the prepreg can bemade in a more suitable range. Note that, the average particle diametercan be measured by a particle diameter distribution measuring device.

The amount of the inorganic filler (A3) in the first resin compositionused in the present invention is preferably made in a range whereby aratio of content of the inorganic filler (A3) with respect to the solidcontent as a whole when making the first resin layer becomes preferably1 to 50 wt %, more preferably 2 to 40 wt %, furthermore preferably 3 to30 wt %. By making the ratio of content of the inorganic filler (A3) inthe first resin layer in the above range, the cured shaped article whichis obtained by curing the prepreg of the present invention is kept smallin surface roughness of the surface of the first resin layer side whilethe effect of decrease of the linear expansion coefficient is enhancedmore.

Further, the first resin composition used in the present invention may,in accordance with need, contain a curing accelerator. The curingaccelerator is not particularly limited, but, for example, an aliphaticpolyamine, aromatic polyamine, secondary amine, tertiary amine,imidazole derivative, organic acid hydrazide, dicyan diamide and itsderivatives, urea derivatives, etc. may be mentioned. Among these, animidazole derivative is particularly preferable.

The imidazole derivative is not particularly limited so long as it is acompound which has an imidazole structure, but, for example,2-ethylimidazole, 2-ethyl-4-methylimidazole,bis-2-ethyl-4-methylimidazole, 1-methyl-2-ethylimidazole,2-isopropylimidazole, 2,4-dimethylimidazole, 2-heptadecylimidazole, andother alkyl substituted imidazole compounds; 2-phenylimidazole,2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole,1-benzyl-2-ethylimidazole, 1-benzyl-2-phenylimidazole, benzimidazole,2-ethyl-4-methyl-1-(2′-cyanoethyl)imidazole, and other imidazolecompounds which are substituted by hydrocarbon groups which contain ringstructures such as aryl groups or aralkyl groups etc. may be mentioned.These may be used alone or may be used in two or more types.

The amount when mixing in a curing accelerator may be suitably selectedin accordance with the purpose of use, but is preferably 0.1 to 20 partsby weight with respect to 100 parts by weight of the polargroup-containing alicyclic olefin polymer (A1) as the first resin, morepreferably 0.1 to 10 parts by weight, furthermore preferably 0.1 to 5parts by weight.

Furthermore, the first resin composition used in the present inventionmay include, for the purpose of improving the flame retardance of theprepreg, for example, a halogen-containing flame retardant or aphosphoric acid ester flame retardant or another flame retardant whichis mixed into a resin composition for formation of a general electricalinsulating film. The amount when mixing in a flame retardant ispreferably 100 parts by weight or less with respect to 100 parts byweight of the polar group-containing alicyclic olefin polymer (A1) asthe first resin, more preferably 60 parts by weight or less.

Further, the first resin composition used in the present invention maycontain, furthermore, in accordance with need, a flame retardant aid,heat resistance stabilizer, weather resistance stabilizer, antiagingagent, UV absorber (laser processing enhancing agent), leveling agent,antistatic agent, slip agent, antiblocking agent, anticlouding agent,lubricant, dye, natural oil, synthetic oil, wax, emulsifying agent,magnetic material, dielectric characteristic adjuster, toughening agent,or other ingredient. The ratios of these optional ingredients added maybe suitably selected in a range not detracting from the object of thepresent invention.

The method of production of the first resin composition used in thepresent invention is not particularly limited. The above ingredients maybe mixed as they are or may be mixed in the state dissolved or dispersedin an organic solvent. Part of the ingredients may be dissolved ordispersed in an organic solvent to prepare a composition and theremaining ingredients may be mixed into that composition.

(Second Resin Composition)

Next, for second resin composition forming the second resin layer willbe explained. The second resin composition used in the present inventionhas a composition which is different from the above-mentioned firstresin composition. That is, at least one of the types and contents ofthe resin and other ingredients which form the resin composition, themolecular weight of the resin, etc. differ. Note that, in the prepreg ofthe present invention, between the above-mentioned first resin layer andthe fiber base material which is contained in the second resin layer, asexplained later, the B layer which is comprised of the second resincomposition and which does not contain the fiber base material isinterposed, and the B layer can exhibit a buffering ability of nottransmitting the relief shapes of the fiber base material surfacedirectly to the first resin layer. That is, the B layer functions as abuffer layer. In particular, in the present invention, the first resincomposition which forms the first resin layer and the second resincomposition which forms the second resin layer have differentcompositions whereby it is believed that an interface is easily formedbetween the B layer and first resin layer and the buffer function isexhibited well.

The second resin which is contained in the second resin composition usedin the present invention is not particularly limited, but in the sameway as the first resin which is contained in the above-mentioned firstresin composition, a resin which has cross-linkable functional groups orcross-linkable carbon-carbon unsaturated bonds is preferable. Asspecific examples of the second resin, ones similar to theabove-mentioned first resin may be mentioned. As the second resin, froma viewpoint similar to the first resin, an alicyclic olefin polymerwhich has polar groups is preferable. Below, a polar group-containingalicyclic olefin polymer as the second resin to be included in thesecond resin composition is defined as a “polar group-containingalicyclic olefin polymer (B1)” and the case using a polargroup-containing alicyclic olefin polymer (B1) as the second resin willbe explained as an example. Note that, in the following explanation, itis possible to similarly suitably apply this in the case of using aresin other than a polar group-containing alicyclic olefin polymer (B1).

As the polar group-containing alicyclic olefin polymer (B1) as thesecond resin, for example, it is possible to use one similar to thepolar group-containing alicyclic olefin polymer (A1) used for the abovementioned first resin composition, but from the viewpoint of making thecured article of the second resin layer excellent in elasticity or heatresistance, it is preferable to use one which has a resin composition ormolecular weight different from the polar group-containing alicyclicolefin polymer (A1) used for the first resin composition.

The amount of the polar group-containing alicyclic olefin polymer (B1)as the second resin in the second resin composition used in the presentinvention is preferably made in a range whereby the ratio of content ofthe polar group-containing alicyclic olefin polymer (B1) with respect tothe solid content as a whole when made a second resin layer becomes 1 to30 wt %, more preferably 1.5 to 20 wt %, furthermore preferably 2 to 10wt %. In the present invention, by making the ratio of content of thepolar group-containing alicyclic olefin polymer (B1) in the second resinlayer in the above range, it is possible to improve the formability ofthe prepreg of the present invention and prevent breakage or dustfall atthe time of work while making the second resin layer good in fluiditywhen heating and laminating the obtained prepreg on a substrate andmaking the laminate flatness and substrate bondability excellent.

Further, the second resin composition used in the present invention maycontain, in addition to the polar group-containing alicyclic olefinpolymer (B1) as the second resin, a curing agent (B2). The curing agent(B2) is not particularly limited. For example, it is possible to use onesimilar to the curing agent (A2) used in the above-mentioned first resincomposition.

In the second resin composition used in the present invention, theamount of the curing agent (B2) is preferably in a range whereby theratio of content of the curing agent (B2) with respect to the solidcontent as a whole when made a second resin layer becomes preferably 3to 35 wt %, more preferably 5 to 30 wt %, furthermore preferably 10 to25 wt %. By making the ratio of content of the curing agent (B2) in thesecond resin layer in the above range, the cured shaped article which isobtained by curing the prepreg of the present invention can be madeexcellent in mechanical strength and electrical characteristics, so thisis preferred.

Furthermore, the second resin composition used in the present inventionpreferably contains, in addition to the polar group-containing alicyclicolefin polymer (B1) as the second resin and the curing agent (B2), aninorganic filler (B3). By further including the inorganic filler (B3),it is possible to make the cured shaped article which is obtained bycuring the prepreg of the present invention low in linear expansioncoefficient.

The inorganic filler (B3) used in the present invention is notparticularly limited, but, for example, calcium carbonate, magnesiumcarbonate, barium carbonate, zinc oxide, titanium oxide, magnesiumoxide, magnesium silicate, calcium silicate, zirconium silicate,hydrated alumina, magnesium hydroxide, aluminum hydroxide, bariumsulfate, silica, talc, clay, etc. may be mentioned. Among these as well,from the viewpoint of improving the cured shaped article which isobtained by curing the prepreg of the present invention in electricalcharacteristics and heat resistance, silica is preferable.

Further, in the present invention, as the inorganic filler (B3) which isincluded in the second resin composition, an inorganic filler which istreated at its surface by a surface treatment agent is preferable. Byusing such a surface treated filler, even if adding a large amount ofinorganic filler, it can be made to disperse well, it is possible toincrease the elasticity of the cured article of the second resin layer,and, further, it is possible to reduce the linear expansion coefficient.

The surface treatment agent which is used for surface treatment of theinorganic filler (B3) used in the present invention is not particularlylimited, but a silane coupling agent, stearic acid and other organicacid, etc. may be mentioned, but from the viewpoint of the excellentdispersability of the inorganic filler and the good fluidity of theresin composition, a silane coupling agent is preferable.

The silane coupling agent is not particularly limited, but a silanecoupling agent which has functional groups which can react with thepolar groups provided in the polar group-containing alicyclic olefinpolymer (B1) is preferable. As such functional groups, for example, anamino group, carboxyl group, methacryloyl group, isocyanate group, epoxygroup, etc. may be mentioned. Among these, an amino group, carboxylgroup, and epoxy group are preferable, while an amino group is morepreferable.

When using a silane coupling agent as a surface treatment agent, theamount of surface treatment of the inorganic filler (B3) is preferably0.1 to 2 wt % based on the amount of the inorganic filler before thesurface treatment (100 wt %), more preferably 0.5 to 1.5 wt %.

Further, as the inorganic filler (B3), a nonconductive one which doesnot cause the obtained electrical insulating layer to drop in dielectriccharacteristics is preferable. Further, the inorganic filler (B3) is notparticularly limited in shape. A spherical shape, fiber shape, plateshape, etc. are also possible, but to make the dispersability and theresin fluidity of the resin composition better, a fine spherical shapeis preferable.

The inorganic filler (B3) has an average particle diameter of preferably0.2 to 3 μm, more preferably 0.25 to 1 μm. By using the inorganic filler(B3) having an average particle diameter in the above range, it ispossible to raise the impregnability of the second resin composition inthe fiber base material and improve the fluidity of the second resinlayer when heating and laminating the obtained prepreg on the substrate.

The amount of the inorganic filler (B3) in the second resin compositionused in the present invention is preferably made in a range whereby aratio of content when making the second resin layer becomes greater thanthe ratio of content of the inorganic filler (A3) which is contained inthe first resin layer (including case of ratio of content of 0 wt %).Specifically, the ratio of content of the inorganic filler (B3) withrespect to the solid content as a whole (except fiber base material)when making the second resin layer is preferably 50 to 85 wt %, morepreferably 55 to 80 wt %, furthermore preferably 60 to 70 wt % in range.In the present invention, by making the ratio of content of theinorganic filler (B3) in the second resin layer in the above range, itis possible to keep low the linear expansion coefficient of the curedshaped article which is obtained by curing the prepreg of the presentinvention. Due to this, it is possible to make the cured shaped articleexcellent in heat resistance.

Further, the second resin composition used in the present invention, inthe same way as the above-mentioned first resin composition, maycontain, for example, a curing accelerator or a flame retardant and,furthermore, in accordance with need, may contain a flame retardant aid,heat resistance stabilizer, weather resistance stabilizer, antiagingagent, UV absorber (laser processing enhancing agent), leveling agent,antistatic agent, slip agent, antiblocking agent, anticlouding agent,lubricant, dye, natural oil, synthetic oil, wax, emulsifying agent,magnetic material, dielectric characteristic adjuster, toughening agent,or another other ingredient. The ratios of these optional ingredientsadded may be suitably selected in a range not detracting from the objectof the present invention.

The method of production of the second resin composition used in thepresent invention is not particularly limited. The above ingredients maybe mixed as they are or may be mixed in the state dissolved or dispersedin an organic solvent. Part of the ingredients may be dissolved ordispersed in an organic solvent to prepare a composition and theremaining ingredients may be mixed into that composition.

(Prepreg)

Next, the prepreg of the present invention will be explained. Theprepreg of the present invention is comprised of a first resin layerwhich is comprised of the above-mentioned first resin composition and asecond resin layer which is comprised of the above-mentioned secondresin composition. The second resin layer contains the fiber basematerial. Further, in the prepreg of the present invention, the secondresin layer is provided with a fiber base material-containing layerwhich contains a fiber base material, an A layer which is positioned atthe opposite side of the first resin layer side of the fiber basematerial-containing layer and which does not contain the fiber basematerial, and a B layer which is positioned at the first resin layerside of the fiber base material-containing layer and which does notcontain the fiber base material. Further, in the prepreg of the presentinvention, the thickness of the B layer which forms the second resinlayer is smaller than the thickness of the first resin layer.

Here, FIG. 1 is a schematic view which shows one example of a prepregaccording to the present invention. As shown in FIG. 1, the prepreg ofthe present invention is provided with a first resin layer 10 and asecond resin layer 20. The second resin layer 20 can be configuredprovided with, from the first resin layer 10 side, a B layer (uppersecond resin layer) 21, fiber base material-containing layer 22, and Alayer (lower second resin layer) 23. The first resin layer 10 is, forexample, used as the plateable layer on the surface of which a platedconductor is formed by the plating method. Further, the second resinlayer 20 is, for example, used as an adhesive layer for adhesion withthe substrate at its surface. In this case, when heating and laminatingthe obtained prepreg to the substrate, the first resin layer preferablydoes not become fluid and does not change in thickness, further can bemaintained in a state excellent in surface flatness. On the other hand,the second resin layer preferably exhibits fluidity and can exhibitexcellent bondability with respect to the substrate on which the prepregis to be laminated in the A layer 23.

The first resin layer 10 is a layer which is comprised of the firstresin composition. Further, the B layer 21 is a layer which is comprisedof the second resin composition, contacts the first resin layer 10, anddoes not contain the fiber base material. The thickness t2_(U) isthinner than the thickness t1 of the first resin layer 10. The fiberbase material-containing layer 22 is a layer which is comprised of thefiber base material and second resin composition and is formed byimpregnating the fiber base material with the second resin composition.Furthermore, the A layer 23 is a layer which is comprised of the secondresin composition and is a layer which is joined with the fiber basematerial-containing layer 22 and is formed at the opposite side to the Blayer 21. In the prepreg of the present invention, the thickness t2_(U)of the B layer 21 corresponds to the distance between the first resinlayer 10 and the fiber base material-containing layer 22.

Below, while suitably referring to FIG. 1, the prepreg of the presentinvention and method of production of the same will be explained indetail. The prepreg of the present invention is produced by the methodof production of the following (1) or (2).

(1) Method comprising step A of using the first resin composition toform the first resin layer 10, step B of superposing the fiber basematerial on the formed first resin layer 10, and, after this step B,step C of impregnating the second resin composition in the fiber basematerial to form the second resin layer 20. Note that, in the method ofproduction of this (1), in step C, when impregnating the second resincomposition in the fiber base material, the B layer 21 is formed betweenthe fiber base material and the first resin layer 10.

Further, in the method of production of this (1), as a method of (1a),instead of step B, it is possible to adopt step B′ of forming the Blayer 21 which is comprised of the second resin composition on theformed first resin layer 10 before superposing the fiber base materialon the first resin layer 10 and step B″ of superposing the fiber basematerial through the B layer 21 which is comprised of the second resincomposition, and following these steps, step C of impregnating thesecond resin composition in the fiber base material to form the fiberbase material-containing layer 22 and the A layer 23.

(2) Method comprising step A of using the first resin composition toform the first resin layer 10 and step D of superposing the fiber basematerial in which the second resin composition is impregnated on theformed first resin layer 10 to form the second resin layer 20.

Note that, in the methods of production of (2), as a method of (2a),after the step D of superposing the fiber base material in which thesecond resin composition is impregnated on the first resin layer 10 toform part of the second resin layer 20, it is possible to adopt themethod of applying or casting the second resin composition on the fiberbase material to form the second resin layer 20.

In the method of (1), it is possible to apply, spray, or cast theabove-mentioned first resin composition on the support and dry this toform the first resin layer 10, then superpose the fiber base material onthe first resin layer 10 and impregnate the above-mentioned second resincomposition in the fiber base material while applying or casting it onthe fiber base material and drying it to thereby form on the first resinlayer 10, in order from the first resin layer 10 side, the B layer 21,fiber base material-containing layer 22, and A layer 23. In this method,the fiber base material is superposed on the first resin layer 10 and,in that state, the second resin composition is impregnated in the fiberbase material while applying or casting it on the fiber base material sothat part of the second resin composition which is impregnated in thefiber base material reaches the interface with the first resin layer 10and seeps out from the fiber base material and thereby, between thefirst resin layer 10 and the fiber base material, the B layer 21 isformed to an extremely thin thickness, specifically, a thickness smallerthan the first resin layer (thickness t2_(U) of B layer 21<thickness t1of first resin layer). Further, due to this, the B layer 21 isinterposed between the first resin layer 10 and the fiber base materialand is present as a buffer layer for preventing these first resin layer10 and fiber base material from directly contacting.

In the method of (1a), the above-mentioned first resin composition isapplied, spray, or cast on the support and dried to thereby form a firstresin layer 10, then the above-mentioned second resin composition isapplied or cast on the first resin layer 10 to form a layer comprised ofthe second resin composition on the first resin layer 10, then, withoutdrying, the fiber base material is superposed on this, theabove-mentioned second resin composition is further added to this toimpregnate the fiber base material while applying or casting on thefiber base material and then drying it and thereby form on the firstresin layer 10, in order from the first resin layer 10 side, the B layer21, fiber base material-containing layer 22, and the A layer 23. In thismethod, by applying or casting the second resin composition on the firstresin layer 10, when forming the layer comprised of the second resincomposition, adopting the condition that the thickness t2_(U) of the Blayer 21 becomes thinner than the thickness t1 of the first resin layeris desirable. In particular, in this case, when superposing the fiberbase material on the layer comprised of the second resin composition,due to surface tension etc., part of the second resin composition whichforms the layer comprised of the second resin composition is taken intothe fiber base material in some cases, so adopting the conditionconsidering such a phenomenon is desirable.

The methods of (2) and (2a) are methods of, rather than applying etc.the second resin composition on the fiber base material to impregnatethe fiber base material with the second resin composition to form thesecond resin layer, impregnating the fiber base material with the secondresin composition in advance and using this to form the second resinlayer. The second resin composition can be impregnated in the fiber basematerial by, for example, placing the fiber base material on any supportand applying etc. this with the second resin composition. At this time,furthermore, by superposing a protective film and pressing (ironing)from above by a roller etc., impregnation of the second resincomposition in the fiber base material may be promoted. With thesemethods, the step of impregnating the fiber base material with thesecond resin composition in advance is included. In this respect, thework becomes complicated, so as the method of production of the prepregof the present invention, the method of (1) or (1a) is preferable.

Note that, in the above method, when applying, spraying, or casting thefirst resin composition on the support or when applying, spraying, orcasting the second resin composition on the first resin layer 10 or onthe fiber base material, the first resin composition or the second resincomposition is preferably, if necessary, applied, sprayed, or cast withthe addition of an organic solvent. When using a resin composition towhich an organic solvent is added, the first resin composition isapplied, spray, or cast on the support, then the organic solvent isdried off to thereby form the first resin layer, but it is also possibleto apply or cast the second resin composition it in multiple stages, andwhen impregnating it, it may be dried in the middle of the process or itmay be dried after finishing applying or casting to become the desiredthickness.

Further, as the support used in this method, a resin film or metal foiletc. may be mentioned. As the resin film, a polyethylene terephthalatefilm, polypropylene film, polyethylene film, polycarbonate film,polyethylene naphthalate film, polyarylate film, nylon film, etc. may bementioned. Among these films, from the viewpoint of the heat resistance,chemical resistance, peel property, etc., a polyethylene terephthalatefilm or polyethylene naphthalate film is preferable. As the metal foil,copper foil, aluminum foil, nickel foil, chrome foil, gold foil, silverfoil, etc. may be mentioned. Note that, the surface roughness Ra of thesupport is usually 300 nm or less, preferably 150 nm or less, morepreferably 100 nm or less.

Furthermore, as the material of the fiber base material, PET(polyethylene terephthalate) fiber, aramide fiber, ultra high molecularweight polyethylene fiber, polyamide (nylon) fiber, and liquid crystalpolyester fiber, and other organic fibers; glass fiber, carbon fiber,alumina fiber, tungsten fiber, molybdenum fiber, titanium fiber, steelfiber, boron fiber, silicon carbide fiber, silica fiber, and otherinorganic fibers; etc. may be mentioned. Among these, organic fiber andglass fiber are preferable, in particular, aramide fiber, liquid crystalpolyester fiber, and glass fiber are preferable. As glass fiber, fibersof E glass, NE glass, S glass, D glass, H glass, T glass, etc. may besuitably used. Further, as the form of the fiber base material, the formof plain weave or twill weave or other woven fabrics or the form ofnonwoven fabric etc. may be mentioned. The thickness of the fiber basematerial may be determined in accordance with the thickness tgc of thefiber base material-containing layer 22, but from the viewpoint ofmaking the prepreg a thin film, 30 μm or less is preferable, and 10 to30 μm is more preferable. If too thin, the handling becomes difficult,while if too thick, the resin layer becomes relatively thin and thewiring embedding ability sometimes becomes insufficient.

In the present invention, the thickness t2_(U) of the B layer 21 is lessthan the thickness t1 of the first resin layer 10, preferably over 0 μmto 5 μm, more preferably over 0 μm to 2 μm, furthermore preferably 0.1μm to 1.5 μm, particularly preferably 0.2 μm to 1.5 μm. In the presentinvention, the B layer 21 is formed between the first resin layer 10 andthe fiber base material-containing layer 22 and the thickness t2_(U) ofthe B layer 21 is made in the above range, but from the viewpoint offorming the interface between the first resin layer and the second resinlayer well, an over 0 μm thickness is necessary. On the other hand, fromthe viewpoint of not being affected by the presence of the B layer andthe function of the first resin layer, which is different from thesecond resin layer, being sufficiently exhibited, it has to be madethinner than the thicknesses t1 of the first resin layer 10. By adoptingsuch a configuration, the B layer 21 functions as a buffer layer and thecured shaped article which is obtained by curing the prepreg of thepresent invention can be suppressed in variation of surface roughnessand made excellent in surface flatness. Further, due to this, it ispossible to effectively prevent the occurrence of uneven plating whenforming a plated conductor on the surface of the first resin layer 10side by the plating method. As a result, the cured shaped articlebecomes excellent in peel strength (bondability between cured shapedarticle and plated conductor), fine wiring formability, and electricalcharacteristics. Further, when laminated on a substrate with reliefshapes, even if the second resin composition becomes fluid, the fiberbase material will not move or twist and therefore a multilayer boardfree of variation in characteristics in the plane can be obtained.

Note that, other than the B layer 21, the first resin layer 10, thefiber base material-containing layer 22, and the A layer 23 are notparticularly limited in thicknesses, but the following ranges arepreferable.

That is, the thicknesses t1 of the first resin layer 10 may be greaterthan the thicknesses t2_(U) of the B layer 21, but the specificthickness of the thickness t1 of the first resin layer 10 is preferably7 μm or less, more preferably 2 to 7 μm, furthermore preferably 2.5 to 6μm. By making the thickness t1 of the first resin layer 10 in thisrange, the obtained cured shaped article can be made good in peelstrength. Further, as the first resin layer 10, from the viewpoint ofeffectively preventing occurrence of uneven plating, a variation ofthickness of ±1.5 μm in range is preferable, ±1 μm in range is morepreferable, and ±0.5 μm in range is furthermore preferable.

Further, the thickness tgc of the fiber base material-containing layer22 is preferably 30 μm or less, more preferably 10 to 30 μm. By makingthe thickness tgc of the fiber base material-containing layer 22 in thisrange, the obtained cured shaped article can be made good in wiringembedding ability or elasticity. Furthermore, the thickness t2_(L) ofthe A layer 23 is suitably preferably 25% or more with respect to thetotal thickness of the prepreg of the present invention (that is,t1+t2_(U)+tgc+t2_(L)), more preferably 25 to 70%, furthermore preferably40 to 65%. As the specific thickness, 9 to 35 μm is preferable, while 15to 30 μm is more preferable. In the present invention, the thicknesst2_(U) of the B layer 21 is made in the above range and the thicknesst2_(L) of the A layer 23 is made in the above ratio with respect to thetotal thickness of the prepreg to thereby make the position of the fiberbase material in the second resin layer 20 a position close to the firstresin layer 10 side. Due to this, even when making the prepreg of thepresent invention a thin film, when laminating the prepreg of thepresent invention on the circuit patterns from the A layer 23 side, itis possible to effectively prevent that the fiber base material isexposed at the surface of the first resin layer 10 side by pressedagainst the circuit patterns. Further, due to this, the effect ofsuppression of variation of the surface roughness of the cured shapedarticle which is obtained by curing the prepreg of the present inventioncan be enhanced more. Furthermore, when laminated on a substrate, thefiber base material will not be twisted, so the flatness afterlamination can be improved and, furthermore, it is possible toeffectively prevent warping of the substrate.

Further, the total thickness (that is, t1+t2_(U)+tgc+t2_(L)) of theprepreg of the present invention is determined by the thicknesses of thedifferent layers, but is preferably 20 to 100 μm, more preferably 25 to80 μm, particularly preferably 30 to 60 μm.

As the method of applying the first resin composition and the secondresin composition, dip coat, roll coat, curtain coat, die coat, slitcoat, gravure coat, etc. may be mentioned.

Further, the drying temperature of drying them, after applying etc. thefirst resin composition and second resin composition, is preferably madea temperature of an extent where the first resin composition and secondresin composition do not cure, but is usually 20 to 300° C., preferably30 to 200° C. Further, the drying time is usually 30 seconds to 1 hour,preferably 1 minute to 30 minutes.

Note that, in the prepreg of the present invention, the first resinlayer 10 and second resin layer 20 (B layer 21, fiber basematerial-containing layer 22, and A layer 23) which form the prepreg arepreferably in an uncured or semicured state. By making these the uncuredor semicured state, the adherability of the first resin layer and thesecond resin layer which form the prepreg of the present invention andthe adherability of the second resin layer 20 (layer acting as adhesivelayer) and substrate can be made high. Here, “uncured” means the statewhere when dipping a prepreg of the present invention in a solvent whichis able to dissolve the first resin (for example, polar group-containingalicyclic olefin polymer (A1)) and a solvent which is able to dissolvethe second resin (for example, polar group-containing alicyclic olefinpolymer (B1)), substantially all of the first resin and second resindissolve. Further, “semicured” means the state of being cured halfway toan extent enabling further curing upon heating, preferably a state whereparts of the first resin and second resin (specifically, amounts of 7 wt% or more and amounts where parts remain) are dissolved in a solventable to dissolve the first resin and a solvent able to dissolve thesecond resin or a state where the volume after dipping the shapedarticle in the solvent for 24 hours is 200% or more of the volume beforedipping (swell rate).

Even when the first resin layer 10 and second resin layer 20 which formthe prepreg of the present invention are uncured or semicured in state,from viewpoint of making the adherability of the second resin layer 20better while keeping the first resin layer 10 from flowing when heatingand laminating the prepreg of the present invention on the substrate atthe surface of the second resin layer 20 side, the viscosity of thefirst resin composition (viscosity in case of not containing volatileingredient such as organic solvent) is preferably made one higher thanthe viscosity of the second resin composition. In particular, in thepresent invention, by making the first resin layer 10 a thickness t1 of7 μm or less and making the variation of thickness±1 μm in range andmaking the viscosity of the first resin composition which forms thefirst resin layer 10 higher than the viscosity of the second resincomposition which forms the second resin layer 20, when heating andlaminating the prepreg of the present invention on the substrate at thesurface of the second resin layer 20 side, it is possible to improve theadherability at the second resin layer 20 side, while the first resinlayer 10 does not become fluid, so the flatness can be maintained. Forthis reason, the cured shaped article which is obtained by curing theprepreg of the present invention can be made one which is small invariation of surface roughness, excellent in surface flatness, and canform a plated conductor layer which is substantially free from unevenplating.

Further, regarding the viscosity of the first resin composition whichforms the first resin layer 10 and the viscosity of the second resincomposition which forms the second resin layer 20, the viscosity of thefirst resin composition is preferably made to become higher than theviscosity of the second resin composition by suitably adjusting theformulation of the composition etc., but suitably, as the viscosity ofthe second resin composition used in the present invention, the minimummelt viscosity at 100° C. to 130° C. in range is preferably less than3000 Pa·s, more preferably less than 1000 Pa·s, furthermore preferablyless than 500 Pa·s, particularly preferably less than 100 Pa·s. Thelower limit is normally made 10 Pa·s or so. On the other hand, theviscosity of the first resin composition is made 3000 Pa·s or more.Furthermore, the difference of viscosity of the first resin compositionand the second resin composition is preferably 500 Pa·s or more. Bymaking the viscosities of the first resin composition and the secondresin composition in this range, when heating and laminating the prepregof the present invention on the substrate, the first resin layer doesnot flow and the first resin layer becomes hard to change in thickness,while the second resin layer exhibits fluidity, so the laminatedflatness on a substrate with relief shapes becomes good. Note that, theviscosity can be measured by a rotary type rheometer or otherviscoelasticity measuring device.

(Laminate)

The laminate of the present invention is obtained by laminating theabove-mentioned prepreg of the present invention on a base materialthrough the surface of the second resin layer side. The laminate of thepresent invention should be one which is comprised of at least theabove-mentioned prepreg of the present invention which is laminated, butis preferably one obtained by laminating a substrate which has aconductor layer on its surface and an electrical insulating layer whichis comprised of the cured product of the prepreg of the presentinvention. Note that, at this time, the prepreg of the present inventionis configured laminated with the substrate through the second resinlayer, so the surface of the electrical insulating layer is made onewhich is formed by the first resin layer among the first resin layer andsecond resin layer of the prepreg of the present invention.

The substrate which has a conductor layer on its surface is one whichhas a conductor layer on the surface of an electrical insulatingsubstrate. The electrical insulating substrate is formed by curing aresin composition which contains a known electrical insulating material(for example, alicyclic olefin polymer, epoxy resin, maleimide resin,(meth)acrylic resin, diallyl phthalate resin, triazine resin, polyphenylether, glass, etc.). The conductor layer is not particularly limited,but is usually a layer which includes wiring which are formed by aconductive metal or other conductor and may further include variouscircuits as well. The configurations, thicknesses, etc. of the wiringand circuits are not particularly limited. As specific examples of asubstrate which has a conductor layer on its surface, a printed circuitboard, silicon wafer board, etc. may be mentioned. The substrate whichhas a conductor layer on its surface has a thickness of usually 10 μm to10 mm, preferably 20 μm to 5 mm, more preferably 30 μm to 2 mm.

The substrate which has a conductor layer on its surface used in thepresent invention is preferably pretreated on the surface of theconductor layer so as to improve the adhesion with the electricalinsulating layer. As the method of pretreatment, known art can be usedwithout particular limitation. For example, if the conductor layer iscomprised of copper, the oxidizing method of bringing a strong alkalineoxidizing solution into contact with the conductor layer surface to forma layer of copper oxide on the conductor surface and roughen it, themethod of oxidizing the conductor layer surface by the previous method,then reducing it by sodium borohydride, formalin, etc., the method ofdepositing plating on the conductor layer to roughen it, the method ofbringing an organic acid into contact with the conductor layer todissolve the grain boundaries of the copper and roughen the layer, themethod of forming a primer layer on the conductor layer by a thiolcompound, silane compound, etc. and the like may be mentioned. Amongthese, from the viewpoint of the ease of maintaining the shapes of finewiring patterns, the method of bringing an organic acid into contactwith the conductor layer to dissolve the grain boundaries of the copperand roughen the layer and the method of using thiol compounds or silanecompounds etc. to form primer layer are preferable.

The laminate of the present invention can usually be produced by hotpressing the prepreg of the present invention on a substrate which has aconductor layer on its surface.

As the method of hot pressing, the method of superposing the prepregwith the support so that the second resin layer which forms the prepregis contiguous with the conductor layer of the substrate explained aboveand using a press laminator, press machine, vacuum laminator, vacuumpress, roll laminator, or other pressure device for hot pressing(lamination) may be mentioned. By hot pressing, it is possible to jointhe conductor layer on the substrate surface and the insulating adhesivefilm with substantially no clearance at their interface.

The temperature of the hot pressing operation is usually 30 to 250° C.,preferably 70 to 200° C., the applied pressure is usually 10 kPa to 20MPa, preferably 100 kPa to 10 MPa, and the pressing time is usually 30seconds to 5 hours, preferably 1 minute to 3 hours. Further, the hotpressing is preferably performed under reduced pressure so as to improveburying wiring patterns into the insulating adhesive film or prepreg andprevent the formation of bubbles. The pressure of the reduced pressureunder which the hot pressing is performed is usually 100 kPa to 1 Pa,preferably 40 kPa to 10 Pa. According to the above hot pressingoperation, by suitably adjusting the temperature conditions etc., it ispossible to laminate the prepreg of the present invention on a basematerial in the uncured state, semicured state, or cured state.

The thus obtained laminate of the present invention is obtained usingthe above-mentioned prepreg of the present invention, so is small invariation of surface roughness, high in surface flatness, and excellentin formability of conductor layer with substantially no uneven plating.For this reason, this can be suitably used for application as anelectrical insulating layer of a multilayer circuit board.

(Multilayer Circuit Board)

Below, the method of production of a multilayer circuit board which isobtained using the laminate of the present invention will be explained.

First, the laminate of the present invention is formed with via holes orthrough holes which pass through the electrical insulating layer. Thevia holes are formed for connecting the different conductor layers whichform a multilayer circuit board when forming a multilayer circuit board.The via holes and through holes can be formed by chemical treatment suchas photolithography or by physical treatment such as drilling, laserirradiation, and plasma etching. Among these methods, the method using alaser (CO₂ gas laser, excimer laser, UV-YAG laser, etc.) enables finevia holes to be formed without causing a drop in the characteristics ofthe electrical insulating layer, so this is preferred.

Next, the electrical insulating layer of the laminate, specifically thesurface of the first resin layer of the prepreg which forms thelaminate, is roughened by surface roughening treatment. The surfaceroughening treatment is performed so as to enhance the adhesion with theconductor layer which is formed on the electrical insulating layer.

The electrical insulating layer has a surface average roughness Ra ofpreferably 0.05 μm to less than 0.5 μm, more preferably 0.06 μm to lessthan 0.3 μm, while the surface 10-point average roughness Rzjis ispreferably 0.3 μm to less than 4 μm, more preferably 0.5 μm to less than2 μm. Note that, in this Description, Ra is the arithmetic averageroughness which is shown in JIS B 0601-2001. The surface 10-pointaverage roughness Rzjis is the 10-point average roughness which is shownin JIS B 0601-2001 Annex 1.

The method of surface roughening treatment is not particularly limited,but the method of bringing the surface of the electrical insulatinglayer (that is, the surface of the first resin layer of the prepreg)into contact with an oxidizing compound etc. may be mentioned. As theoxidizing compound, an inorganic oxidizing compound or organic oxidizingcompound or other known compound which has an oxidizing ability may bementioned. From the ease of control of the surface average roughness ofthe electrical insulating layer, use of an inorganic oxidizing compoundor organic oxidizing compound is particularly preferable. As theinorganic oxidizing compound, a permanganate, chromic acid anhydride,dichromate, chromate, persulfate, active manganese dioxide, osmiumtetraoxide, hydrogen peroxide, periodide, etc. may be mentioned. As theorganic oxidizing compound, dicumyl peroxide, octanoyl peroxide,m-chloroperbenzoate, peracetate, ozone, etc. may be mentioned.

The method of using an inorganic oxidizing compound or organic oxidizingcompound to roughen the surface of the electrical insulating layer isnot particularly limited. For example, the method of dissolving theabove oxidizing compound in a solvent which can dissolve it so as toprepare an oxidizing compound solution and bringing this into contactwith the surface of the electrical insulating layer may be mentioned.

The method of bringing the oxidizing compound solution into contact withthe surface of the electrical insulating layer is not particularlylimited, but, for example, the dipping method of dipping the electricalinsulating layer in the oxidizing compound solution, the buildup methodof utilizing the surface tension of the oxidizing compound solution toplace the oxidizing compound solution on the electrical insulatinglayer, the spraying method of spraying the oxidizing compound solutionon the electrical insulating layer, or any other method may also beused. By performing the surface roughening treatment, it is possible toimprove the adhesion of the electrical insulating layer with theconductor layer and other layers.

The temperature and the time by which these oxidizing compound solutionsare brought into contact with the surface of the electrical insulatinglayer may be freely set by considering the concentration and type of theoxidizing compound, method of contact, etc., but the temperature isusually 10 to 150° C., preferably 20 to 100° C., while the time isusually 0.5 to 60 minutes, preferably 1 to 40 minutes.

Note that, to remove the oxidizing compound after the surface rougheningtreatment, the surface of the electrical insulating layer after thesurface roughening treatment is washed with water. Further, when asubstance which cannot be washed off by just water is deposited on thesurface, the surface is further washed by a washing solution which candissolve that substance or another compound is brought into contact withthe surface to convert the substance into one which can be dissolved inwater and then the surface is washed by water. For example, whenbringing an aqueous solution of potassium permanganate or an aqueoussolution of sodium permanganate or other alkali aqueous solution intocontact with the electrical insulating layer, to remove the film ofmanganese dioxide which is formed, it is possible to using a mixedsolution of hydroxylamine sulfate and sulfuric acid or other acidicaqueous solution to neutralize/reduce the surface, then wash it bywater.

Next, after the electrical insulating layer of the laminate is treatedto roughen its surface, a conductor layer is formed on the surface ofthe electrical insulating layer (that is, the surface of the first resinlayer of the prepreg) and the inside wall surfaces of the via holes orthrough holes.

The method of formation of the conductor layer is pertained, from theviewpoint of enabling formation of a conductor layer which is excellentin adhesion, using the electroless plating method.

For example, when using electroless plating to form a conductor layer,first, before taming a metal thin layer on the surface of the electricalinsulating layer, the general practice has been to deposit silver,palladium, zinc, cobalt, or another catalyst nuclei on the electricalinsulating layer (that is, first resin layer of prepreg). The method ofdepositing catalyst nuclei on the electrical insulating layer is notparticularly limited, but, for example, the method of dipping thearticle in a solution obtained by dissolving silver, palladium, zinc,cobalt, or other metal compounds or their salts or complexes in water,alcohol, chloroform or another organic solvent in 0.001 to 10 wt % inconcentration (in accordance with need, also possibly including an acid,alkali, complexing agent, reducing agent, etc.), then reducing the metaletc. may be mentioned.

As the electroless plating solution which is used in the electrolessplating, a known self-catalyst type electroless plating solution may beused. It is not particularly limited in the type of metal, the type ofreducing agent, the type of complexing agent, the concentration ofhydrogen ions, the concentration of dissolved oxygen, etc. which arecontained in the plating solution. For example, an electroless copperplating solution which contains ammonium hypophosphite, hypophosphoricacid, ammonium borohydride, hydrazine, formalin, etc. as a reducingagent; an electroless nickel-phosphorus plating solution which containssodium hypophosphite as a reducing agent; an electroless nickel-boronplating solution which contains dimethylamineborane as a reducing agent;an electroless palladium plating solution; an electrolesspalladium-phosphorus plating solution which contains sodiumhypophosphite as a reducing agent; an electroless gold plating solution;an electroless silver plating solution; an electrolessnickel-cobalt-phosphorus plating solution which contains sodiumhypophosphite as a reducing agent, or other electroless plating solutioncan be used.

After forming the metal thin layer, the substrate surface may be broughtinto contact with a rustproofing agent to make it rustproof. Further,after forming the metal thin layer, the metal thin layer may be heatedto raise the adhesiveness. The heating temperature is usually 50 to 350°C., preferably 80 to 250° C. Note that, at this time, the heating may beperformed under pressed conditions. As the pressing method at this time,for example, the method of using a hot press, a pressurizing and heatingroll, and other physical pressing means may be mentioned. The pressurewhich is applied is usually 0.1 to 20 MPa, preferably 0.5 to 10 MPa. Ifthis range, high adhesion can be secured between the metal thin layerand the electrical insulating layer.

The thus formed metal thin layer is formed with a plating-use resistpattern and the plating is further grown over it by electroplating orother wet plating (thickening plating). Next, the resist is removed andthe surface is further etched to etch the metal thin layer into thepattern shapes and form the conductor layer. Therefore, the conductorlayer which is formed by this method is usually comprised of thepatterned metal thin layer and the plating which is grown over that.

For example, using the above obtained multilayer circuit board as thesubstrate for producing the above-mentioned laminate, the prepreg of thepresent invention is hot pressed on this and cured to form an electricalinsulating layer and the above-mentioned method is used to form aconductor layer over this. By repeating these steps, it is possible tofurther increase the number of layers. Due to this, the desiredmultilayer circuit board can be obtained.

Note that, in the above, the technique of making the thicknesses t2_(U)of the B layer 21 thinner than the thickness t1 of the first resin layer10 to provide a prepreg which can give a cured shaped article which issmall in variation of surface roughness, excellent in surface flatness,and can form a plated conductor layer substantially free of unevenplating was explained, but a technique which controls the thicknesst2_(U) of the B layer to over 0 μm to 2 μm may also be used.Alternatively, instead of these techniques, the technique which controlsthe thickness t2_(L) of the A layer 23 to 25% or more of the totalthickness of the prepreg (that is, t1+t2_(U)+tgc+t2_(L)) or thetechnique which controls the thickness of the first resin layer 10 to 7μm or less and the variation of thickness to ±1 μm and makes theviscosity of the first resin composition which forms the first resinlayer 10 higher than the viscosity of the second resin composition whichforms the second resin layer 20 may also be used.

EXAMPLES

Below, examples and comparative examples will be given to morespecifically explain the present invention. Note that, in the examples,the “parts” and “%”, unless particularly indicated otherwise, are basedon weight. The various types of properties were evaluated by thefollowing methods.

(1) Number Average Molecular Weight (Mn) and Weight Average MolecularWeight (Mw) of Alicyclic Olefin Polymer

The alicyclic olefin polymer was measured for number average molecularweight (Mn) and weight average molecular weight (Mw) by gel permeationchromatography (GPC) using tetrahydrofuran as a developing solvent.These were found as values converted to polystyrene.

(2) Hydrogenation Ratio of Alicyclic Olefin Polymer

The ratio of the number of moles of the unsaturated bonds which werehydrogenated with respect to the number of moles of the unsaturatedbonds in the polymer before the hydrogenation was found by measurementof the 400 MHz ¹H-NMR spectrum. This was used as the hydrogenationratio.

(3) Content of Monomer Units Having Carboxylic Anhydride Groups inAlicyclic Olefin Polymer

The ratio of the number of moles of the monomer units which havecarboxylic anhydride groups with respect to the number of moles of totalmonomer units in the polymer was found by measurement of the 400 MHz¹H-NMR spectrum. This was used as the content of monomer units havingcarboxylic anhydride groups of the polymer.

(4) Melt Viscosity

The varnish of the first resin composition and the varnish of the secondresin composition were applied on a thickness 38 μm polyethyleneterephthalate film and dried in a nitrogen atmosphere at 80° C. for 10minutes to obtain a film with support. Further, just the differentcompositions were collected from the film and press formed to preparethickness 600 μm plate-shaped samples. The dynamic viscoelasticity wasmeasured using a Jasco International VAR100 VISCOANALYSER ETC-3 at atemperature elevation rate of 5° C./minute, a starting temperature 50°C., a measurement temperature interval of 2.5° C., and a vibration of 1Hz/deg. The lowest melt viscosity at 100° C. to 130° C. was evaluated bythe following criteria.

A: Less than 500 Pa·s

B: 500 Pa·s to less than 1000 Pa·s

C: 1000 Pa·s or more

(5) Variation of Thickness of First Resin Layer

A cross-section of the obtained prepreg was observed by an opticalmicroscope to thereby measure the variation of thickness of the firstresin layer. This was evaluated by the following criteria.

Good: Less than ±0.5 μm

Fair: ±0.5 μm to less than ±1 μm

Poor: Over ±1 μm or impregnation in fiber base material

(6) Surface Roughness of First Resin Layer (Arithmetic Average RoughnessRa)

Copper of the multilayer printed circuit board surface was dissolved byan ammonium persulfate solution. The obtained first resin layer surfacewas measured for surface roughness (arithmetic average roughness Ra)using a surface shape measuring device (made by Veeco Instruments, Inc.,WYKO NT1100) in a measurement range of 91 μm×120 μm at five locations.The maximum value of surface roughness obtained as a result ofmeasurement was evaluated by the following criteria.

Good: Ra of less than 300 nm

Fair: Ra of 300 nm to less than 500 nm

Poor: Ra of 500 nm or more

(7) Variation of Surface Roughness (Arithmetic Average Roughness Ra) ofFirst Resin Layer

The difference between the maximum value and minimum value of themeasured values of surface roughness (arithmetic average roughness Ra)at five locations obtained by the measurement of the above (6) wascalculated. This was evaluated by the following criteria.

Good: Difference of maximum value and minimum value of Ra of less than50 nm

Fair: Difference of maximum value and minimum value of Ra of 50 nm toless than 150 nm

Poor: Difference of maximum value and minimum value of Ra of 150 nm ormore

(8) Unevenness of Plated Conductor Layer (Unevenness of Plating)

The peel off strength (peel strength) between the insulating layer andcopper plating layer of the multilayer printed circuit board wasmeasured in accordance with JIS C6481-1996 at five locations.

The multilayer printed circuit board being measured is in each caseformed by a similar material. At each measured multilayer printedcircuit board, if there is no difference in the peel strength at thedifferent measurement points, the average value can be considered toshow a uniform value. On the other hand, if there is a difference inlevel of peel strength at each measurement point, it is considered thataverage value of the peel strength falls.

Therefore, the average value of the peel strengths of five locations ofthe multilayer printed circuit board was evaluated by the followingcriteria. The lower the value of the average value, the larger theunevenness of plating judged.

Good: Peel strength of 5N/cm or more

Fair: Peel strength of 3N/cm to less than 5N/cm

Poor: Peel strength of less than 3N/cm

(9) Observation of Cross-Section of Multilayer Printed Circuit Board(Contact of Glass Cloth and Conductor Wiring)

A cross-section of the multilayer printed circuit board was observed.This was evaluated by the following criteria.

Good: Fiber base material did not contact conductor wiring.

Poor: Fiber base material contacted conductor wiring.

Synthesis Example 1

As a first stage of polymerization,5-ethylidene-bicyclo[2.2.1]hept-2-ene(EdNB) 35 molar parts, 1-hexene 0.9molar part, anisole 340 molar parts, and 4-acetoxybenzylidene(dichloro)(4,5-dibromo-1,3-dimesityl-4-imidazolin-2-ylidene)(tricyclohexylphosphine)ruthenium (C1063, made by Wako Pure ChemicalsIndustries, Ltd.) 0.005 molar part were charged into anitrogen-substituted pressure-resistant glass reactor where they werestirred at 80° C. for 30 minutes for a polymerization reaction to obtaina solution of a norbornene-based ring-opening polymer.

Next, as a second stage of polymerization, to the solution which wasobtained in the first stage of polymerization,tetracyclo[9.2.1.0^(2,10).0^(3,8)]tetradeca-3,5,7,12-tetraene (MTF) 35molar parts, bicyclo[2.2.1]hept-2-ene-5,6-dicarboxylic anhydride (NDCA)30 molar parts, anisole 250 molar parts, and 0.01 molar part of C1063were added and stirred at 80° C. for 1.5 hours for a polymerizationreaction to obtain a solution of a norbornene-based ring-openingpolymer. This solution was measured by gas chromatography, whereupon itwas confirmed that substantially no monomers remained. Thepolymerization conversion rate was 99% or more.

Next, to a nitrogen-substituted mixer-equipped autoclave, the obtainedsolution of the ring-opening polymer was charged, 0.03 molar part ofC1063 was added, and the mixture was stirred at 150° C. under a hydrogenpressure of 7 MPa for 5 hours to perform a hydrogenation reaction andobtain a solution of a hydrogenation product of a norbornene-basedring-opening polymer constituted by an alicyclic olefin polymer (P-1).The obtained polymer (P-1) had a weight average molecular weight of60,000, a number average molecular weight of 30,000, and a molecularweight distribution of 2. Further, the hydrogenation rate was 95%, whilethe content of the monomer units which have carboxylic acid anhydridegroups was 30 mol %. The solution of the polymer (P-1) had a solidcontent concentration of 22%.

Synthesis Example 2

Tetracyclo[9.2.1.0^(2,10).0^(3,8)]tetradeca-3,5,7,12-tetraene (MTF) 70molar parts, bicyclo[2.2.1]hept-2-ene-5,6-dicarboxylic anhydride (NDCA)30 molar parts, 1-hexene 0.9 molar part, anisole 590 molar parts, and0.015 molar part of C1063 were charged into a nitrogen-substitutedpressure-resistant glass reactor where they were stirred at 80° C. for 1hour for a polymerization reaction to obtain a solution of anorbornene-based ring-opening polymer. This solution was measured by gaschromatography, whereupon it was confirmed that there were substantiallyno monomers remaining. The polymerization conversion rate was 99% ormore.

Next, to a nitrogen-substituted mixer-equipped autoclave, the obtainedsolution of the ring-opening polymer was charged. This was stirred at150° C. at a hydrogen pressure of 7 MPa for 5 hours for a hydrogenationreaction to obtain a solution of a hydrogenation product of anorbornene-based ring-opening polymer constituted by the alicyclicolefin polymer (P-2). The obtained polymer (P-2) had a weight averagemolecular weight of 50,000, a number average molecular weight of 26,000,and a molecular weight distribution of 1.9. Further, the hydrogenationrate was 97%, while the content of the monomer units which hadcarboxylic anhydride groups was 30 mol %. The solution of the polymer(P-2) had a solid content concentration of 22%.

Synthesis Example 3

Tetracyclo[9.2.1.0^(2,10).0^(3,8)]tetradeca-3,5,7,12-tetraene (MTF) 70molar parts, bicyclo[2.2.1]hept-2-ene-5,6-dicarboxylic anhydride (NDCA)30 molar parts, 1-hexene 6 molar parts, anisole 590 molar parts, and0.015 molar part of C1063 were charged into a nitrogen-substitutedpressure-resistant glass reactor where they were stirred at 80° C. for 1hour for a polymerization reaction to obtain a solution of aring-opening polymer. This solution was measured by gas chromatography,whereupon it was confirmed that substantially no monomers remained. Thepolymerization conversion rate was 99% or more.

Next, to a nitrogen-substituted mixer-equipped autoclave, the obtainedsolution of the ring-opening polymer was charged. This was stirred at150° C. under a hydrogen pressure of 7 MPa for 5 hours to perform ahydrogenation reaction. Next, the obtained hydrogenation reactionsolution was concentrated to obtain a solution of the alicyclic olefinpolymer (P-3). The obtained alicyclic olefin polymer (P-3) had a weightaverage molecular weight of 10,000, a number average molecular weight of5,000, and a molecular weight distribution of 2. Further, thehydrogenation rate was 97%, while the content of monomer units which hadcarboxylic acid anhydride groups was 30 mol %. The solution of thealicyclic olefin polymer (P-3) had a solid content concentration of 55%.

Example 1 Preparation of First Resin Composition

A solution of the alicyclic olefin polymer (P-1) which was obtained inSynthesis Example 1, 45 parts and 6 parts of silica slurry which wasobtained by mixing an inorganic filler constituted by untreatedspherical silica (Admafine (Registered Trademark) SO-C1, made byAdmatechs Company Limited, volume average particle diameter 0.25 μm) 98%and the alicyclic olefin polymer (P-2) which was obtained in SynthesisExample 2, 2% in anisole so as to give a solid content of 75% anddispersing them by a high pressure homogenizer were mixed and stirred bya planetary type mixer for 3 minutes.

To this, a curing agent constituted by a dicyclopentadiene typemultifunctional epoxy resin (EPICLON HP-7200L, made by DIC Corporation,epoxy equivalents: 242 to 252) 3.5 parts, a laser processabilityenhancing agent constituted by2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole 0.1part, a hindered phenol compound constituted bytris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanulate (IRGANOX (RegisteredTrademark) 3114, made by BASF) 0.1 part, a hindered amine compoundconstituted bytetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate(Adekastab (Registered Trademark) LA52, made by ADEKA CORPORATION) 0.05part, and anisole 75.2 parts were mixed and stirred by a planetary typemixer for 3 minutes.

Furthermore, to this, a solution in which a curing acceleratorconstituted by 1-benzyl-2-phenylimidazole was dissolved 50% in anisole0.1 part was mixed. The mixture was stirred by a planetary type mixerfor 5 minutes to obtain a varnish of a first resin composition.

(Preparation of Second Resin Composition)

A solution of the alicyclic olefin polymer (P-2) which was obtained inSynthesis Example 2, 9.1 parts and 84.6 parts of silica slurry which wasobtained by mixing an inorganic filler (B3) constituted bysurface-treated spherical silica (Admafine (Registered Trademark)SC-2500-SXJ, made by Admatechs Company Limited, aminosilane type silanecoupling agent-treated product, volume average particle diameter 0.5 μm)98.5% and the alicyclic olefin polymer (P-3) which was obtained inSynthesis Example 3, 1.5% in anisole so as to give a solid content of78% and treating them by a high pressure homogenizer were mixed andstirred by a planetary type mixer for 3 minutes.

To this, a curing agent constituted by bisphenol A type epoxy resin(Epicoat (Registered Trademark) 828EL, made by Mitsubishi ChemicalCorporation, epoxy equivalents: 184 to 194) 3 parts, multifunctionalepoxy resin (1032H60, made by Mitsubishi Chemical Corporation, epoxyequivalents: 163 to 175) 3 parts, dicyclopentadiene type multifunctionalepoxy resin (EPICLON HP-7200L) 11 parts, an antiaging agent constitutedby tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanulate 0.1 part,dicyclopentadiene type novolac resin (GDP-6140, made by Gun Ei ChemicalIndustry Co., Ltd.) 15 parts, and anisole 2.4 pars were mixed andstirred by a planetary type mixer for 3 minutes. Furthermore, to this, asolution in which a curing accelerator constituted by1-benzyl-2-phenylimidazole was dissolved 50% in anisole 0.3 part wasmixed. The mixture was stirred by a planetary type mixer for 5 minutesto obtain a varnish of a second resin composition.

(Preparation of Prepreg)

The above obtained varnish of the first resin composition was applied ona thickness 38 μm polyethylene terephthalate film (support) using a wirebar, then this was dried in a nitrogen atmosphere at 85° C. for 5minutes to obtain a film with the support on which is formed a firstresin layer 10 (see FIG. 1) which is comprised of an uncured first resincomposition. Note that, the thickness t1 of the first resin layer 10 was6 μm.

Next, a glass cloth (Cloth Type #1027, thickness 20 μm, basis weight 19g/m²) was superposed on the film with the support at the surface wherethe first resin layer 10 was formed, then the above obtained varnish ofthe second resin composition was applied on this using a doctor blade(made by Tester Sangyo Co., Ltd) and auto film applicator (made byTester Sangyo Co., Ltd) while impregnating the glass cloth. Next, thiswas dried in a nitrogen atmosphere at 80° C. for 10 minutes to form, inorder from the support, as shown in FIG. 1, the first resin layer 10, Blayer 21, fiber base material-containing layer 22, and A layer 23 toobtain a total thickness 45 μm prepreg. Further, the obtained prepregwas measured for thickness variation in the surface of the first resinlayer 10 by the above method. The results are shown in Table 1. Further,the obtained prepreg was heated at 180° C. for 60 minutes to therebycause heat curing. A cross-section of the prepreg after the heat curingwas measured using an optical microscope. The thicknesses t1, t2_(U),tgc, and t2_(L) of the different layers (see FIG. 1) are shown inTable 1. Note that, in the present example, a heat cured prepreg wasused to measure the thicknesses of the different layers, but thethicknesses of the layers which form the prepreg do not substantiallychange before and after the heat curing (similar in Examples 2 to 7 andComparative Examples 1 to 5).

(Preparation of Laminate)

Next, separate from the above, a thickness 0.8 μm insulating board wasprovided on its two sides with comb-like patterns of conductor wiringwith conductor intervals of 100 and conductor heights of 18 Theconductor wiring was brought into contact with an organic acid tomicroetch them and obtain an inside layer substrate.

At the two sides of this inside layer substrate, the above obtainedprepregs were superposed so that the surfaces at the A layer 23 sideswere at the inside layer substrate sides, then the assembly was pressedby a primary pressing operation. The primary pressing operation was hotpressing by a vacuum laminator which was provided with heat resistantrubber press plates at the top and bottom under a reduced pressure of200 Pa at a temperature of 110° C. and a pressure of 0.1 MPa for 90seconds. Furthermore, a hydraulic press apparatus which was providedwith metal press plates at the top and bottom was used to hot press theassembly at a press bonding temperature of 110° C. and 1 MPa for 90seconds. Next, the support was peeled off to thereby obtain a laminateof prepreg layers and an inside layer substrate. Furthermore, thelaminate was allowed to stand in an air atmosphere at 180° C. for 60minutes and the first resin layer 10 and second resin layer 20 whichwere contained in the prepreg were made to cure to form electricalinsulating layers on the inside layer substrate.

(Swelling Treatment Step)

The obtained laminate was dipped while shaking in a 60° C. aqueoussolution which was prepared to contain a swelling solution (“SwellingDip Securiganth P”, made by Atotech, “Securiganth” is a registeredtrademark) 500 ml/liter and sodium hydroxide 3 g/liter for 15 minutes,then was rinsed.

(Oxidizing Treatment Step)

Next, the laminate which was treated for swelling was dipped whileshaking in an 80° C. aqueous solution which was prepared to contain anaqueous solution of permanganate (“Concentrate Compact CP”, made byAtotech) 500 ml/liter and a concentration of sodium hydroxide of 40g/liter for 20 minutes, then was rinsed.

(Neutralizing/Reduction Treatment Step)

Next, the laminate which was treated by oxidation was dipped in a 40° C.aqueous solution which was prepared to contain an aqueous solution ofhydroxylamine sulfate (“Reduction Securiganth P 500”, made by Atotech,“Securiganth” is a registered trademark) 100 ml/liter and sulfuric acid35 ml/liter for 5 minutes to neutralize and reduce it, then was rinsed.

(Cleaner/Conditioner Step)

Next, the laminate which was treated by neutralization/reduction wasdipped in a 50° C. aqueous solution which was prepared to contain acleaner/conditioner aqueous solution (“Alcup MCC-6-A”, made by Uyemura &Co., Ltd. “Alcup” is a registered trademark) of a concentration of 50ml/liter for 5 minutes to treat it with the cleaner and conditioner.Next, the laminate was dipped in 40° C. rinsing water for 1 minute, thenwas rinsed.

(Soft Etching Step)

Next, the laminate which was treated by the cleaner/conditioner wasdipped in an aqueous solution which was prepared to contain a sulfuricacid concentration of 100 g/liter and sodium persulfate of 100 g/literfor 2 minutes to be soft etched, then was rinsed.

(Pickling Step)

Next, the laminate which was treated by soft etching was dipped in anaqueous solution which was prepared to contain a sulfuric acidconcentration of 100 g/liter for 1 minute to be pickled, then wasrinsed.

(Catalyst Imparting Step)

Next, the laminate which was treated by pickling was dipped in a 60° C.Pd salt-containing plating catalyst aqueous solution which was preparedto contain Alcup Activator MAT-1-A (product name, made by Uyemura & Co.,Ltd. “Alcup” is a registered trademark) 200 ml/liter, Alcup ActivatorMAT-1-B (product name, made by Uyemura & Co., Ltd. “Alcup” is aregistered trademark) 30 ml/liter, and sodium hydroxide 0.35 g/liter for5 minutes, then was rinsed.

(Activation Step)

Next, the laminate which was treated by catalyst imparting was dipped inan aqueous solution which was prepared to contain Alcup Reducer MAB-4-A(product name, made by Uyemura & Co., “Alcup” is a registered trademark)20 ml/liter and Alcup Reducer MAB-4-B (product name, made by Uyemura &Co., Ltd. “Alcup” is a registered trademark) 200 ml/liter at 35° C. for3 minutes to reduce the plating catalyst, then was rinsed.

(Accelerator Treatment Step)

Next, the laminate which was treated by activation was dipped in anaqueous solution which was prepared to contain Alcup Accelerator MEL-3-A(product name, made by Uyemura & Co., Ltd. “Alcup” is a registeredtrademark) 50 ml/liter at 25° C. for 1 minute.

(Electroless Plating Step)

The thus obtained laminate was dipped in an electroless copper platingsolution which was prepared to contain Thru-Cup PEA-6-A (product name,made by Uyemura & Co., Ltd. “Thru-Cup” is a registered trademark) 100ml/liter, Thru-Cup PEA-6-B-2X (product name, made by Uyemura & Co. Ltd.)50 ml/liter, Thru-Cup PEA-6-C (product name, made by Uyemura & Co. Ltd.)14 ml/liter, Thru-Cup PEA-6-D (product name, made by Uyemura & Co. Ltd.)15 ml/liter, Thru-Cup PEA-6-E (product name, made by Uyemura & Co. Ltd.)50 ml/liter, and 37% formalin aqueous solution 5 ml/liter, while blowingin air, at a temperature of 36° C. for 20 minutes for electroless copperplating so as to form an electroless plating film on the laminatesurface (surface of first resin layer 10 comprised of first resincomposition). Next, the laminate was annealed in an air atmosphere at150° C. for 30 minutes.

The annealed laminate was electroplated with copper to form a thickness30 μm electroplated copper layer. Next, the laminate was heat treated at180° C. for 60 minutes to thereby obtain a two-sided two-layermultilayer printed circuit board comprised of a laminate on whichcircuits are formed by conductor layers which are comprised of the metalthin film layers and electroplated copper layers. The obtainedmultilayer printed circuit board was evaluated by the above methods forthe surface roughness of first resin layer (arithmetic average roughnessRa), the variation of the surface roughness of first resin layer(arithmetic average roughness Ra), the bondability of insulating layerand the metal layer (peel strength), and contact of the glass cloth andconductor layer by observation of the cross-section. The results areshown in Table 1.

Example 2

A varnish of a first resin composition which was obtained in the sameway as Example 1 was used to obtain a film with the support which wasformed with a first resin layer 10 with a thicknesses t1 of 3 μm.Further, the surface of the obtained film with the support on which thefirst resin layer 10 was formed was coated with the varnish of thesecond resin composition which was obtained in the same way as Example 1by using a wire bar, then glass cloth (Cloth Type #1027, thickness 20μm, basis weight 19 g/m²) was superposed on this and bonded to it. Next,furthermore, the varnish of the second resin composition was applied onthis using a doctor blade (made by Tester Sangyo Co., Ltd) and an autofilm applicator (made by Tester Sangyo Co., Ltd). Next, this was driedin a nitrogen atmosphere at 80° C. for 10 minutes to form, in order fromthe support, as shown in FIG. 1, the first resin layer 10, B layer 21,fiber base material-containing layer 22, and A layer 23 to obtain atotal thickness 45 μm prepreg. Further, the obtained prepreg wasmeasured for thickness variation in the surface of the first resin layer10 in the same way as Example 1. The results are shown in Table 1.Further, the obtained prepreg was heated at 180° C. for 60 minutes tothereby cause heat curing. A cross-section of the prepreg after the heatcuring was measured using an optical microscope. The thicknesses t1,t2_(U), tgc, and t2_(L) of the different layers (see FIG. 1) are shownin Table 1.

Further, the same procedure was followed as in Example 1 to prepare amultilayer printed circuit board. Using the prepared multilayer printedcircuit board, the same procedure was followed as in Example 1 forevaluation. The results are shown in Table 1.

Example 3

A varnish of a first resin composition which was obtained in the sameway as Example 1 was used to obtain a film with the support on which wasformed a first resin layer 10 with a thicknesses t1 of 2.5 μm. Further,a glass cloth (Cloth Type #1000, thickness 10 μm, basis weight 11 g/m²)was superposed on the obtained film with the support at the surface onwhich the first resin layer 10 was formed, then the varnish of thesecond resin composition which was obtained in the same way as Example 1was applied on this using a doctor blade (made by Tester Sangyo Co.,Ltd) and an auto film applicator (made by Tester Sangyo Co., Ltd) whileimpregnating the glass cloth, next, this was dried in a nitrogenatmosphere at 80° C. for 10 minutes to form, in order from the support,as shown in FIG. 1, the first resin layer 10, B layer 21, fiber basematerial-containing layer 22, and A layer 23 to obtain a total thickness39.5 μm prepreg. Further, the obtained prepreg was measured forthickness variation in the urface of the first resin layer 10 in thesame way as Example 1. The results are shown in Table 1. Further, theobtained prepreg was heated at 180° C. for 60 minutes to thereby causeheat curing. A cross-section of the prepreg after the heat curing wasmeasured using an optical microscope. The thicknesses t1, t2_(U), tgc,t2_(L) of the different layers (see FIG. 1) are shown in Table 1.

Further, the same procedure was followed as in Example 1 to prepare amultilayer printed circuit board. Using the prepared multilayer printedcircuit board, the same procedure was followed as in Example 1 forevaluation The results are shown in Table 1.

Example 4

A varnish of a first resin composition which was obtained in the sameway as Example 1 was used to obtain a film with the support on which wasformed a first resin layer 10 with a thicknesses t1 of 6 μm. Further, avarnish of a second resin composition which was obtained in the same wayas Example 1 was coated on the obtained film with the support at thesurface on which the first resin layer 10 was formed using a wire bar,then a glass cloth (Cloth Type #1035, thickness 30 μm, basis weight 30g/m²) was superposed on this and bonded to it. Next, furthermore, thevarnish of the second resin composition was applied on this using adoctor blade (made by Tester Sangyo Co., Ltd) and an auto filmapplicator (made by Tester Sangyo Co., Ltd), next, this was dried in anitrogen atmosphere at 80° C. for 10 minutes to form, in order from thesupport, shown in FIG. 1, the first resin layer 10, B layer 21, fiberbase material-containing layer 22, and A layer 23 to obtain a totalthickness 68 μm prepreg. Further, the obtained prepreg was measured forthickness variation in the surface of the first resin layer 10 in thesame way as Example 1. The results are shown in Table 1. Further, theobtained prepreg was heated at 180° C. for 60 minutes to thereby causeheat curing. A cross-section of the prepreg after the heat curing wasmeasured using an optical microscope. The thicknesses t1, t2_(U), tgc,and t2_(L) of the different layers (see FIG. 1) are shown in Table 1.

Further, the same procedure was followed as in Example 1 to prepare amultilayer printed circuit board. Using the prepared multilayer printedcircuit board, the same procedure was followed as in Example 1 forevaluation. The results are shown in Table 1.

Example 5

A varnish of a first resin composition which was obtained in the sameway as Example 1 was used to obtain a film with the support on which wasformed a first resin layer 10 with a thicknesses t1 of 6 μm.

Further, a varnish of a second resin composition which was obtained inthe same way as Example 1 was coated on a thickness 38 μm polyethyleneterephthalate film (support) using a doctor blade to prepare a layerwhich was comprised of the varnish of the second resin composition onthe support film, then a glass cloth (Cloth Type #1027, thickness 20 μm,basis weight 19 g/m²) was superposed on this and bonded to it. Next,furthermore, a varnish of the second resin composition was applied onthis using a doctor blade, then this was dried in a nitrogen atmosphereat 80° C. for 10 minutes to obtain a prepreg of the second resincomposition of a thicknesses of 44 μm.

Next, the prepreg of the second resin composition was superposed at thesecond resin composition layer side on the film with the support onwhich the first resin composition layer 10 was formed. A vacuumlaminator which was provided with press plates made of heat resistantrubber at the top and bottom was used to reduce the pressure to 200 Paand laminate the layers by hot press bonding at a temperature of 80° C.and a pressure of 0.1 MPa for 30 seconds. After this, the support whichwas used at the time of preparation of the prepreg of the second resincomposition was peeled off to form in order from the support, shown inFIG. 1, the first resin layer 10, B layer 21, fiber basematerial-containing layer 22, and A layer 23 to obtain a total thickness50 μm prepreg. Further, the obtained prepreg was measured for thicknessvariation in the surface of the first resin layer 10 in the same way asExample 1. The results are shown in Table 1. Further, the obtainedprepreg was heated at 180° C. for 60 minutes to thereby cause heatcuring. A cross-section of the prepreg after the heat curing wasmeasured using an optical microscope. The thicknesses t1, t2_(U), tgc,and t2_(L) of the different layers (see FIG. 1) are shown in Table 1.

Further, the same procedure was followed as in Example 1 to prepare amultilayer printed circuit board. Using the prepared multilayer printedcircuit board, the same procedure was followed as in Example 1 forevaluation The results are shown in Table 1.

Example 6

An A layer 23 of a total thickness 50 μm prepreg obtained in the sameway as Example 5 was applied with a varnish of a second resincomposition which was obtained in the same way as Example 1 by a wirebar, then was dried in a nitrogen atmosphere at 80° C. for 5 minutes toobtain a total thickness 55 μm prepreg. Further, the obtained prepregwas measured for thickness variation in the surface of the first resinlayer 10 in the same way as Example 1. The results are shown in Table 1.Further, the obtained prepreg was heated at 180° C. for 60 minutes tothereby cause heat curing. A cross-section of the prepreg after the heatcuring was measured using an optical microscope. The thicknesses t1,t2_(U), tgc, and t2_(L) of the different layers (see FIG. 1) are shownin Table 1.

Further, the same procedure was followed as in Example 1 to prepare amultilayer printed circuit board. Using the prepared multilayer printedcircuit board, the same procedure was followed as in Example 1 forevaluation. The results are shown in Table 1.

Example 7 Preparation of Second Resin Composition

A solution of the alicyclic olefin polymer (P-2) which was obtained inSynthesis Example 2, 20 parts and 31.2 parts of silica slurry which wasobtained by mixing an inorganic filler (B3) constituted bysurface-treated spherical silica (Admafine (RegisteredTrademark)SC-2500-SXJ, made by Admatechs Company Limited, aminosilanetype silane coupling agent-treated product, volume average particlediameter 0.5 μm) 98.5% and the alicyclic olefin polymer (P-3) which wasobtained in Synthesis Example 3, 1.5% in anisole so as to give a solidcontent of 78% and treating them by a high pressure homogenizer weremixed and stirred by a planetary type mixer for 3 minutes.

To this, a curing agent constituted by bisphenol A type epoxy resin(Epicoat (Registered Trademark) 828EL, made by Mitsubishi ChemicalCorporation, epoxy equivalents: 184 to 194) 6.5 parts, multifunctionalepoxy resin (1032H60, made by Mitsubishi Chemical Corporation, epoxyequivalents: 163 to 175) 6.5 parts, dicyclopentadiene typemultifunctional epoxy resin (EPICLON HP-7200L) 24 parts, an antiagingagent constituted by tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanulate0.2 part, dicyclopentadiene type novolac resin (GDP-6140, made by Gun EiChemical Industry Co., Ltd.) 32.6 parts, and anisole 18 pars were mixedand stirred by a planetary type mixer for 3 minutes. Furthermore, tothis, a solution in which a curing accelerator constituted by1-benzyl-2-phenylimidazole was dissolved 50% in anisole 0.65 part wasmixed. The mixture was stirred by a planetary type mixer for 5 minutesto obtain a varnish of a second resin composition.

(Preparation of Prepreg)

A varnish of a first resin composition which was obtained in the sameway as Example 1 was used to obtain a film with a support which wasformed with a first resin layer 10 with a thicknesses t1 of 5 μm.Further, a glass cloth (Cloth Type #1000, thickness 10 μm, basis weight11 g/m²) was superposed on the film with the support at the surfacewhere the first resin layer 10 was formed, then the above obtainedvarnish of the second resin composition was applied on this using adoctor blade while impregnating the glass cloth. Next, this was dried ina nitrogen atmosphere at 80° C. for 10 minutes to form, in order fromthe support, as shown in FIG. 1, the first resin layer 10, B layer 21,fiber base material-containing layer 22, and A layer 23 to obtain atotal thickness 45 μm prepreg. Further, the obtained prepreg wasmeasured for thickness variation in the surface of the first resin layer10 by the above method. The results are shown in Table 1. Further, theobtained prepreg was heated at 180° C. for 60 minutes to thereby causeheat curing. A cross-section of the prepreg after the heat curing wasmeasured using an optical microscope. The thicknesses t1, t2_(U), tgc,and t2_(L) of the different layers (see FIG. 1) are shown in Table 1.

Further, the same procedure was followed as in Example 1 to prepare amultilayer printed circuit board. Using the prepared multilayer printedcircuit board, the same procedure was followed as in Example 1 forevaluation. The results are shown in Table 1.

Comparative Example 1

A varnish of a second resin composition which was obtained in the sameway as Example 1 was coated on a thickness 38 μm polyethyleneterephthalate film (support) using a doctor blade to prepare a layercomprised of the varnish of the second resin composition on the supportfilm, glass cloth (Cloth Type #1027, thickness 20 μm, basis weight 19g/m²) was superposed on this and bonded to it, and the varnish of thesecond resin composition was applied on this using a doctor blade. Next,this was dried in a nitrogen atmosphere at 80° C. for 10 minutes toprepare a total thickness 45 μm prepreg. Further, the obtained prepregwas heated at 180° C. for 60 minutes to thereby cause heat curing. Across-section of the prepreg after the heat curing was measured using anoptical microscope. The thicknesses t1, t2_(U), tgc, and t2_(L) of thelayers (see FIG. 1) are shown in Table 1. Note that, the prepreg whichwas obtained in Comparative Example 1 did not have the first resin layer10.

Further, the same procedure was followed as in Example 1 to prepare amultilayer printed circuit board. Using the prepared multilayer printedcircuit board, the same procedure was followed as in Example 1 forevaluation. The results are shown in Table 1.

Comparative Example 2

Except for not adding the anisole which was mixed in alone at 75.2 partsin Example 1, the same procedure was followed as in Example 1 to preparea varnish of the first resin composition.

Further, a glass cloth (Cloth Type #1027, thickness 20 μm, basis weight19 g/m²) was applied using a two-side coater with the above obtainedvarnish of the first resin composition to a 4 μm thickness and, further,at the opposite side to this, with the varnish of the second resincomposition which was obtained at Example 1. Next, this was dried in anitrogen atmosphere at 80° C. for 10 minutes to obtain a total thickness45 μm prepreg. Further, the obtained prepreg was measured for thicknessvariation in the surface of the first resin layer 10 in the same way asExample 1. The results are shown in Table 1. Further, the obtainedprepreg was heated at 180° C. for 60 minutes to thereby cause heatcuring. A cross-section of the prepreg after the heat curing wasmeasured using an optical microscope. The thicknesses t1, t2_(U), tgc,and t2_(L) (see FIG. 1) are shown in Table 1.

Further, the same procedure was followed as in Example 1 to prepare amultilayer printed circuit board. Using the prepared multilayer printedcircuit board, the same procedure was followed as in Example 1 forevaluation. The results are shown in Table 1.

Comparative Example 3 Production of Carrier Material

A varnish of a first resin composition which was obtained in the sameway as Example 1 was coated on a thickness 38 μm polyethyleneterephthalate film (support) using a wire bar and dried in a nitrogenatmosphere at 85° C. for 2 minutes to obtain a first resin layer filmwith the support which was formed with a thickness 6 μm first resinlayer which was comprised of an uncured first resin composition.

Further, separate from this, the varnish of the second resin compositionwhich was obtained in the same way as Example 1 was coated on athickness 38 μm polyethylene terephthalate film (support) using a doctorblade and dried in a nitrogen atmosphere at 85° C. for 10 minutes toobtain a second resin layer film with the support which was formed witha thickness 26 μm second resin layer which was comprised of an uncuredsecond resin composition.

(Production of Prepreg)

Further, the thus obtained first resin layer film with the support andsecond resin layer film with the support were used to sandwich a glasscloth (Cloth Type #1027, thickness 20 μm, basis weight 19 g/m²) in astate backed with supports, then a vacuum laminator which was providedwith press plates made of heat resistant rubber at the top and bottomwas used to reduce the pressure to 200 Pa and laminate the layers by hotpress bonding at a temperature of 80° C. and a pressure of 0.1 MPa for30 seconds to obtain a prepreg which is formed with a first resin layer,glass cloth, and second resin layer in that order and which has a totalthickness of 45 μm. Further, the obtained prepreg was measured forthickness variation in the surface of the first resin layer 10 in thesame way as Example 1. The results are shown in Table 1. Further, theobtained prepreg was heated at 180° C. for 60 minutes to thereby causeheat curing. A cross-section of the prepreg after the heat curing wasmeasured using an optical microscope. The thicknesses t1, t2_(U), tgc,and t2_(L) of the layers (see FIG. 1) are shown in Table 1.

Further, the same procedure was followed as in Example 1 to prepare amultilayer printed circuit board. Using the prepared multilayer printedcircuit board, the same procedure was followed as in Example 1 forevaluation. The results are shown in Table 1.

Comparative Example 4

A varnish of a second resin composition which was obtained in the sameway as Example 1 was coated on a thickness 38 μm polyethyleneterephthalate film (support) using a doctor blade to prepare a layerwhich was comprised of the varnish of the second resin composition on asupport film and a glass cloth (Cloth Type #1027, thickness 20 μm, basisweight 19 g/m²) was superposed on it and bonded to it. Furthermore, thevarnish of the second resin composition was applied on this using thedoctor blade. Next, this was dried in a nitrogen atmosphere at 80° C.for 8 minutes to obtain a prepreg of the second resin composition of atotal thickness of 44 μm. Furthermore, a varnish of a first resincomposition which was obtained in the same way as Example 1 was appliedon the second resin composition layer of the prepreg of the second resincomposition using a wire blade, then this was dried in a nitrogenatmosphere at 80° C. for 3 minutes. Furthermore, a thickness 38 μmpolyethylene terephthalate (support) was superposed on the layer whichwas comprised of the first resin composition. A vacuum laminator whichis provided with press plates made of heat resistant rubber at the topand bottom was used to reduce the pressure to 200 Pa and laminate thelayers by hot press bonding at a temperature of 80° C. and a pressure of0.1 MPa for 30 seconds, then the support which contacts the second resincomposition layer was peeled off to prepare a total thickness 45 μmprepreg.

Further, the obtained prepreg was measured for thickness variation inthe surface of the first resin layer 10 in the same way as Example 1.The results are shown in Table 1. Further, the obtained prepreg washeated at 180° C. for 60 minutes to thereby cause heat curing. Across-section of the prepreg after the heat curing was measured using anoptical microscope. The thicknesses t1, t2_(U), tgc, and t2_(L) of thelayers (see FIG. 1) are shown in Table 1.

Further, the same procedure was followed as in Example 1 to prepare amultilayer printed circuit board. Using the prepared multilayer printedcircuit board, the same procedure was followed as in Example 1 forevaluation. The results are shown in Table 1.

Comparative Example 5

A varnish of a first resin composition which was obtained in the sameway as Example 1 was used to obtain a film with a support which wasformed with a first resin layer with a thickness t1 of 2 μm.

Further, a varnish of a second resin composition which was obtained inthe same way as Example 1 was coated on a thickness 38 μm polyethyleneterephthalate film (support) using a doctor blade to prepare a layerwhich was comprised of the varnish of the second resin composition on asupport film and a glass cloth (Cloth Type #1027, thickness 20 μm, basisweight 19 g/m²) was superposed on it and bonded to it. Next,furthermore, the varnish of the second resin composition was applied onthis using a doctor blade and, next, this was dried in a nitrogenatmosphere at 80° C. for 10 minutes to obtain a thickness 48 μm prepregof the second resin composition.

Next, the prepreg of the second resin composition was superposed at thesecond resin composition layer side on the film with the support onwhich the first resin composition layer 10 was formed. A vacuumlaminator which is provided with press plates made of heat resistantrubber at the top and bottom was used to reduce the pressure to 200 Paand laminate the layers by hot press bonding at a temperature of 80° C.and a pressure of 0.1 MPa for 30 seconds. After this, the support whichwas used for preparation of the prepreg of the second resin compositionwas peeled off to obtain a prepreg which was formed with, in order fromthe support, as shown in FIG. 1, the first resin layer 10, the B layer21, the fiber base material-containing layer 22, and the A layer 23 andwhich has a total thickness of 50 Further, the obtained prepreg wasmeasured for thickness variation in the surface of the first resin layer10 in the same way as Example 1. The results are shown in Table 1.Further, the obtained prepreg was heated at 180° C. for 60 minutes tothereby cause heat curing. A cross-section of the prepreg after the heatcuring was measured using an optical microscope. The thicknesses t1,t2_(U), tgc, and t2_(L) of the layers (see FIG. 1) are shown in Table 1.

Further, the same procedure was followed as in Example 1 to prepare amultilayer printed circuit board. Using the prepared multilayer printedcircuit board, the same procedure was followed as in Example 1 forevaluation. The results are shown in Table 1.

Table 1

TABLE 1 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Comp Comp Comp CompComp ple 1 ple 2 ple 3 ple 4 ple 5 ple 6 ple 7 Ex. 1 Ex. 2 Ex. 3 Ex. 4Ex. 5 Method of production of A B A B C D A E F G H C prepreg*1)Thickness t1 of first resin (μm) 6 3 2.5 6 6 6 5 0 4 3 1 2 layerThickness t2_(u) of B layer (μm) 1 1.5 2 2 4 4 4 10 0 0 4 14 Thicknesstgc of fiber (μm) 20 20 10 30 20 20 10 20 20 20 20 20 basematerial-containing layer Thickness t2_(L) of A layer (μm) 18 20.5 25 3020 25 26 15 21 22 20 14 Total thickness of (μm) 45 45 39.5 68 50 55 4545 45 45 45 50 prepreg Ratio of thickness t2_(L) of (%) 40 46 63 44 4045 58 33 47 49 44 28 A layer to total thickness Ratio of content of (%)24 24 24 24 24 24 24 — 24 24 24 24 inorganic filler in first resin layerRatio of content of (%) 65 65 65 65 65 65 24 65 65 65 65 65 inorganicfiller in second resin layer Variation in thickness (μm) Good Good GoodGood Fair Fair Good — Poor Poor Δ Good of first resin layer beforecuring Viscosity of first resin (Pa · s) C C C C C C C — C C C C layerViscosity of second resin (Pa · s) A A A A A A A A A A A A layer Surfaceroughness of first Good Good Good Good Good Good Good Fair Good GoodFair Good resin layer*2) Variation in surface Good Good Gocd Good GoodGood Fair Poor Poor Poor Poor Fair roughness of first resin layer*3)Unevenness of plating Good Good Good Good Good Good Good Poor Fair FairPoor Good Contact of glass cloth Good Good Good Good Good Good Good GoodGood Good Good Poor and conductor wiring *1)In Table 1, the methods ofproduction are as follows. Method of Production A: Using first resincomposition to form first resin layer 10, then superposing fiber basematerial on first resin layer 10 and impregnating fiber base materialwith second resin composition. Method of Production B: Using first resincomposition to form first resin layer 10, then coating first resin layer10 with second resin composition, next, superposing fiber base materialand further applying second resin composition on that. Method ofProduction C: Using first resin composition to form first resin layer10, then superposing fiber base material impregnated with second resincomposition on first resin layer 10. Method of Production D: In Methodof Production C, further applying and casting second resin compositionon fiber base material impregnated with second resin composition. Methodof Production E: Coating second resin composition on support, thensuperposing fiber base material on that, then applying second resincomposition on that. Method of Production F: Applying first resincomposition from one side of fiber base material, then applying secondresin composition from opposite side. Method of Production G: Separatelypreparing film of first resin composition and film of second resincomposition and using these to sandwich fiber base material. Method ofProduction H: Coating second resin composition on support, thensuperposing fiber base material on that, further applying that with asecond resin composition, drying it, then applying this with first resincomposition. *2)In Table 1, for Comparative Example 1, the surfaceroughness of the B layer 21 which forms the second resin layer is shown.*3)In Table 1, for Comparative Example 1, the variation in the surfaceroughness of the B layer 21 which forms the second resin layer is shown.

As shown in Table 1, when using a prepreg which is formed with a B layerbetween the first resin layer and the fiber base material and has athickness t2_(U) of B layer which is smaller than the thickness t1 ofthe first resin layer, it is learned that the obtained multilayerprinted circuit board is small in surface roughness of the first resinlayer, low in variation of surface roughness, and is formed with aplated conductor layer with no uneven plating on the first resin layer(Examples 1 to 7). Note that, in the prepreg which is obtained in eachexamples, the thickness t2_(L) of the A layer is 25% or more of thetotal thickness of the prepreg. When observing the cross-section of theobtained multilayer printed circuit board, no contact could be observedbetween the glass cloth and conductor wiring and the result was good.Furthermore, these prepregs which were obtained in the examples all hada thickness t2_(U) of the B layer of over 0 μm to 2 μm and, further, hada thickness t1 of the first resin layer of 7 μm or less, and a variationin thickness of the first resin layer (before curing) of ±1 μm in range.Further, in these examples, in each case, as the resin composition whichforms the first resin layer, one higher in viscosity than the resincomposition which forms the second resin layer was used.

On the other hand, when, in accordance with a method similar to theexamples, not forming the first resin layer but producing the prepregsomewhat thicker in thickness of the B layer, it is learned that in theobtained multilayer printed circuit board, the surface roughness at thesurface where the plated conductor layer is formed and the extent ofvariation of the same are inferior (Comparative Example 1).

Further, in a prepreg which is obtained by applying the two sides ofglass cloth by the varnish of the first resin composition and thevarnish of the second resin composition so as to form the first resinlayer and the second resin layer (Comparative Example 2) or in a prepregwhich is obtained by forming the first resin layer and the second resinlayer on separate supports and sandwiching a glass cloth by the firstresin layer and the second resin layer (Comparative Example 3), it islearned that a B layer which is comprised of the second resincomposition and which does not contain the fiber base material is notformed between the first resin layer and the fiber base material andthat the obtained multilayer printed circuit board becomes larger invariation of the surface roughness of the first resin layer andunevenness of plating. In the prepregs which were obtained in thesecomparative examples, unlike the prepregs of the present invention, atwo-layer structure which is comprised of the first resin layer and theB layer is not formed. It is believed that this is a result of the factthat the effect of relief shapes on the surface of the fiber basematerial exerted on the surface for forming the plated conductor layeris not sufficiently buffered.

Furthermore, in a prepreg which is obtained by coating the second resincomposition on a support, then superposing the fiber base material overthis, then further applying this with the second resin composition,drying it, then applying this with the first resin composition(Comparative Example 4), it is learned that the thickness of the firstresin layer ends up becoming too much thinner than the thickness of theB layer and that the obtained multilayer printed circuit board becomeslarger in variation of the surface roughness of the first resin layerand unevenness of plating. Further, even in the case of producing aprepreg by the same method of production as Example 5, when making thethickness of the first resin layer thinner than the thickness of the Blayer (Comparative Example 5), the result is that contact between theglass cloth and the conductor wiring ends up occurring.

REFERENCE SIGNS LIST

-   -   10 . . . first resin layer    -   20 . . . second resin layer    -   21 . . . B layer    -   22 . . . fiber base material-containing layer    -   23 . . . A layer

1. A method of production of the prepreg provided with a first resinlayer and a second resin layer which is formed on the first resin layer,wherein: said first resin layer is formed by a first resin composition,said second resin layer is a layer which comprises a resin layer whichis formed by a second resin composition which is different from saidfirst resin composition and in which a fiber base material is contained,said second resin layer is provided with a fiber basematerial-containing layer which contains said fiber base material, an Alayer which is positioned at an opposite side of said first resin layerside of said fiber base material-containing layer and which does notcontain said fiber base material, and a B layer which is positioned atsaid first resin layer side of said fiber base material-containing layerand which does not contain said fiber base material, said B layer has athickness of over 0 μm to 2 μm, and said B layer has a thickness whichis smaller than the thickness of said first resin layer, the methodcomprising: a step A of using said first resin composition to form saidfirst resin layer, a step B of superposing said fiber base material onsaid first resin layer, and a step C of impregnating said second resincomposition in said fiber base material after said step B, where, whenimpregnating said second resin composition in said fiber base materialin said step C, the B layer is formed between said fiber base materialand said first resin layer.
 2. The method of production of the prepregas set forth in claim 1 further comprising, before superposing saidfiber base material on said first resin layer, forming the B layercomprised of said second resin composition on said first resin layer andsuperposing said fiber base material through the B layer.
 3. A method ofproduction of the prepreg provided with a first resin layer and a secondresin layer which is formed on the first resin layer, wherein: saidfirst resin layer is formed by a first resin composition, said secondresin layer is a layer which comprises a resin layer which is formed bya second resin composition which is different from said first resincomposition and in which a fiber base material is contained, said secondresin layer is provided with a fiber base material-containing layerwhich contains said fiber base material, an A layer which is positionedat an opposite side of said first resin layer side of said fiber basematerial-containing layer and which does not contain said fiber basematerial, and a B layer which is positioned at said first resin layerside of said fiber base material-containing layer and which does notcontain said fiber base material, said B layer has a thickness of over 0μm to 2 μm, and said B layer has a thickness which is smaller than thethickness of said first resin layer, the method comprising: a step A ofusing said first resin composition to form said first resin layer and astep D of superposing said fiber base material in which said secondresin composition is impregnated on said first resin layer to form saidsecond resin layer.
 4. The method of production of the prepreg as setforth in claim 3 further comprising, after superposing said fiber basematerial in which said second resin composition is impregnated on saidfirst resin layer, then further applying or casting said second resincomposition on said fiber base material to form said second resin layer.